TYPE CERTIFICATION - REVIEW CASES

Type III Exit Area Boeing Models 707 and 720 Aircraft - Abbreviated Fire Detector System Cessna Models 180 and 182 Aircraft - Cooling Test for Approval of Turbosuper charger Installation Lockheed Model 382 (C-13OE) Aircraft - Rotor Containment for Air Turbine Motor and Refrigeration Cooling Turbine 209 2 1.5 22 1. 233 237 243 247 251 257 25.9 267 275 Page vi 6 JRu 7 1 8110.6 Page No. l L . . No. 53. Boeing Model 707-300C Aircraft - Access Aisleway at Type II Emergency Exits No. 54. Twin Beech Aircraft - Compliance.with FAR 23, Section 23.735 - Brakes No. 55. Hiller Models UH-12L4, UH-12L and UH-12E-L Helicopters - Maximum Rotorcraft Load Combination Weight (FAR 133) No. 56. Lockheed Model 382 (C-130E) Aircraft - Deletion of Fire Shields from Aluminum Engine Mount Support Beam No. 57. Use of Autopilot as Stability Device When Pitch Trim Compensator is Inoperative - DC-8 No. 58. Fire Resistant Fuel Lines in the Engine Compartment of the Cessna Model 188 Airplane No. 59. Fire Protection of Oil System of Swearingen SA-26T Airplane No. 60. Cessna Crafted Full-Flow Oil Filters Used on Cessna Aircraft No. 61. Review of CAR 6.328 With Particular Regard to Lockheed CL-286 Helicopter Power Control System No. 62. Labeling of Fire Panel - Boeing 707-321C No. 63. Application of CAR 4h.356(e) to the Aero Commander Model 1121 No. 64. Boeing Request for Review Case on 737 APU Fuel Icing Protection No. 65. Piper PA-31 Aircraft/CAR 3.359 Amendment 3-7 No. 66. Interpretation of FAR -25.857(e)(l) for the Boeing 7.47 Aircraft No. 67. Fire Resistant Requirements for Oil Cooler Located in Fire Zone of Windecker Model AC-7 Airplane ‘279 281 283 .287 293 305 311 315 321 329 331 335 337 341 345 Page vii 8110.6 6 Jan 71 Page No. Q& No. 68. Cutout Switch for Elevator Trim Systems on Ted Smith Aircraft Company Models 600 and 601 351 No. 69. Induction System Alternate Air Door Requirement for Windecker Model AC-7 Airplane with Fuel Injection Engine 355 Page viii CHAPTERI.. GUIDELINES I* _-- PURPOSE. This chapter sets forth the guidelines governing the initiating and applicability of a Review Case. 2 * RFGIONAL, REQUEST. A Review Case should be requested hy regional personnel ---- whenever: ii " The applicant requests LI revie.w, by Washington, of a determination of compliance made by the region in conjunction with a specific ‘1pp 1 ication for il type certificate or a supplemental type certificate, or lr . When regional personnel first encounter a specific design feature compliance determination problem for one or more models, and for which the existing standards are considered inadequate or inappro- priate, 3 . K'+NUFACTURER REQUEST. A manufacturer may make a request for review to ._.. the region or to Washington. Requests received directly from a manu- facturer will be referred to the appropriate region. 4. WASHINGTON ACTION. Upon receipt of a request for a Review Case the Washington Office will evaluate the facts in the matter and set forth its findings and applicability of the findings over the Director's signature. In those situations wherein the same problem arises and involves another aircraft type similar to that considered in a previous Review Case, the findings of the related Review Case may be applied at the discretion of the Regional Office. In each such instance the Region is to advise the Washington Office of such application and recommend as to the need for a regulatory change. 5. _DlSSEMINATION OF REVIEW CASE INFORMATION. Copies of Review Cases will be made available to the public upon request. All such requests should be transmitted to the Chief, Engineering and Manufacturing Division, Attention: FS-103. Certain portions of the Review Cases may be deleted prior to release. These include: 3 * Information furnished by any person that would not customarily be released to the public. b. Information furnished and accepted in confidence. c. Opinions, advice, deliberations or recommendations made in the course of developing the official action by the agency. h-20. RESERVED. Page l(and 2) CHAPTER 2. PROCEDURES b 21. 22. 23. 24. GENERAL. The basic procedures set forth below should be followed in handling Review Cases. Exceptions may be allowed in cases or urgency or special importance. PREPARATION OF REVIEW CASE REQUESTS. Requests prepared by the Regional Office must include adequate documentation. Such documentation must include, but not be limited to, the necessary regulation(s), the prob- lem or differences of opinion, background material, analysis and conclu- sion by both the region and the applicant, etc. Such requests should be transmitted to the Chief, Engineering and Manufacturing Division, Washington, D. C. PREPARATION OF REVIEW CASES. Washington will complete its analysis, assembly of additional pertinent information, prepare findings, and complete clearances and coordination with other pertinent offices. If necessary, a conference will be arranged in Washington, before actual Review Case issuance, between the representative(s) of the manufacturer concerned, the cognizant Regional Office, and the Engineering and Manufacturing Division. In such instances, advance notice will be given to the parties concerned. ISSUANCE OF REVIEW CA=. Upon completion of the revie& and the findings made, the Review Case will be assigned a number and issued to the region affected for implementation, and to other holders of this Handbook for information purposes. 25.-30. RESEKVED. Chap 2 Par 21 Page 3(and 4) CHAPTER 3. REVIEW CASE ISSUANCES 31. GENERAL. This chapter contains each Review Case, including the find- ings by Washington, for which a request has been made for review of a compliance determination with one or more specific regulatory type certification requirements. Upon receipt of the issuance, the region affected is to take the action indicated therein. c Chap 3 Par 31 Page 5(and 6) b Jnn 71 8?1.0.6 RFa'v'IEW CASE NO . i . BELL HELICOPTER COMPANY REQUEST FOR REVIEW OF p DECISION BY THE SOUTHWEST REGION RELATED TC INTERPKETATJON OF SECTION 6.11(ej(3) OF THE CTVll, AIR REGULATIONS (Issued 11. June 1963) I . INTRODUCTION --- Tile Bell Helicopter Company has rcquest.ed (t!;r'ough the medium of personal representations) revi.ew and reconsideration of a ciezision by i:he Solrthwest Region relating to interpretation of Civil A!.K Keguiations, Section 6.11(e)(3), which was inatrianental in establ-lsh- ing the certification basis applicable to a modification kit foe Bell Model 47G-2 helicopters. 2. ClIRONOLOGICAL HISTORY ----- - a. By letter to the Southwest Region dated January 31, 1.961, Bell. Helicopter Company submitted for Federal Aviation Agency approval a modification kit identified as Bell Service Ir,struction No. 384. The kit modifications, when incorporated in a Bell Model 476-2 helicopter, result in a helicopter having the gross weight, power, performance, dimensions, and altitude capability of the previously approved Model 47G-2A, except that certain fire protection details are omitted. b. Because of the extensive changes in the kit mcdificdt%on, and the similarity of the resulting helicopter to the Model'47G-2A, the Southwest Reg!on has decided that the kit should be certificated in accordance jrith the regulations applied to the Model 47G-2A. The Southwest Region advises that this decision was given verbally to Mr. Schroder of Bell. I’: . Civil Air Regulations, Section 6.11(e)(3), provCdes t.hae a new application for type certificate shall. be required and the regula- tions, together with all amendments thereto, effec:tive on the date of the new application shall be made applicable for the case where a change in design, configuration, power or weight which the Administrator finds is so extensive as to require a substantially complete investigation of compliance with the regulations. d. It appears that Bell's request for reconsideratioil is based upon their opinion that the changes in design configuration, power, and weight which are involved in the modification kit for Lhe Model 47G-2 helicopter are not so extensive as to require a substantially com- plete investigation of compliance with the regjllations. Otherwise, if Bell agreed that the changes were so extensive as to require a substantially complete investigation of compliance with the Chap 1 Par I Page 7 3. regulations, tile proper course of 'action would have been the submittal of a petition for exemption from the provisions of Section 6.11(e) (3). Since they have not done this, we must conclude that the issue at hand is whether or not the changes involved are such as to require a substantially complete inves- tigatian of compliance with the regulations. FACTS IN THE CASE Ths! pertinent approved models of the Bell Model 47G series are as fsllows: a. b. C. d. Made1 47G-2. This helicopter was certificated under Type Certificate H-1, approved January 20, 1955, on the basis of CAFi, Part 6, dated May 24, 1946. Model 47G-3. This model incorporated a turbosuperchnrged Franklin Model 6VS-335 engine with higher power limits, changes in the airframe and rotor system, and increased gross weight. This model was certificated under Type Certificate 2H-3 approved March 17, 1960, on the basis of CAR, Part 6, dated December 19.56, plus amendments through 6-4. Model 47G-2A. This helicopter is identical to the Model 47G-3 except that it utilizes a Lycoming VO 435 engine. This model was certificated under Type Certificate 2H-3 approved December IO, 1960, on the same regulation basis as the Model 47G-3. Bell Models 47G-3 and 47G-2A differ from each other only in respect to engine installation. Although power limits are the same for both, the Model 47G-3 is capable of higher altitude operation bccause of the turbosupercharging feature. Both models are growth versions of the Model 476-2 and differ from it in the following major respects: (1) Power increased from 200 to 240 horsepower for takeoff. (2) Airspeed limit VNE, sea level, increased from 100 to 105 m.p.h. (3) Maximum weight changed from 2450 to 2850 pounds. (4) Installed metal rotor blades from Model 47J helicopter, with faur feet increase in diameter. (5) Lengthened fuselage and tai 1 rotor drive shaft. (6) Incorporated fire protection changes in engine compartment areas, Chap 3 Par 2 e . There are many and various ct-ranges in the airwnrthiness standards of CAR, Part 6, dated December 1956, plus amendments through 6-4 as compared w.!th tile standards of CAR, Part 6. dated May 1946. However, the only sections of intcrest in this issue are t.!jose relating to engine fire protective features, since the pronosed kit would make the helicopter identical in all essenti.al rtispec.ts to a. Flodel 4K -212 e~cttpt for the E-ire protection cll;icrges i.n the fag .ine compart.cllent 3rd certain minor pqciduction improvement items. Bei claims that i:he addition of the fire protection changes would increese the wei.ght by 15 or 20 pounds. They further sta.te that the fire prctectlon ch,lnges do not material.ly contribute to safety because a fire i.s not iikel;l to occur. It is claimed t:b t no fires hive cdver occurred on the commercial Model 47 ser$es, although a fire of minor consequence dia occur c.n a. mili tdrl. c>cnterpart, r. With respect to the fire protection c!langes w'hiclr were requf.red of both the 47G-'?A and 4'IG-3 modeis in order to comply with CAR, Section 6.480, it is understood that fire-resistant plumbing, redesigned firewalls and seals, and the substitution of materials for certain pa:ts were involved. The requirements under Section 6.480 prescribe cert,ain features for protection against fire in the engine compartment and are intended to ensure that the main and auxiliary rotors and controls remain operable, t he e s s en t. I a 1. rotorcraft structure remains intact, and that the passengers and crew are otherwise protected at least fi.ve minutes after the start of an engine fire to permit a controlled autorotational landing. g, The contention that the fire protective measures proposed for omis-, sion do not materially contribute to safety because of infrequent occurrence of powerplant fires is not cons j;iered va I id I CAR, Fart 6, requires only meager fire protection features ;is compared vi rh CAR. Part 7, for the larger and more powerful transport helicopters, 'I'!, t! small, low-power engine installations are general iy less complic*ated, and experience shows there is less likelihood of f-ire occurring. Therefore, the standards recognize that the occurrence,, of fire is likely to be rare. If this were not RO,'. the more extensive pro- tective features, such as contained in CAR, Part 7, would have been prescribed. 11. The question as to whether or not the fire protection provisions under both the general and detailed sections of Section 6.480 do or do not materially contribute to safety is not one to be resolved by this review. If Bell Helicopter Company believes that a regula- tion is inappropriate and improper, they should take action through normal channels available to them to petition for an exemption or otherwise seek amendment to the requirements. Chap 3 Par 3 Page 9 8110. 6 6 Jan IL 1. Since many of the parLs and*,components comprising the kit were previously approved on either the 47G-2A, 47G-3 or earlier modeis, it is apparent that very little investigation.of compliance with the regulations would be inv.olved in the approval of these changes as now applied in kit form to the Model 476-2. j. The provisions of CAR, Section 6.11 (designationcf applicable regulations) indicate that the intent is to make a judgment of the extent of changes made to the basic type design. Therefore, the provisions are seen to be applicable to the overall excursion from the basic type design, rather than to a series of design changes which, taken separately, might not be considered to be either extensive or require a substantially complete investigation; but when taken as a total group might be judged to be of that extent. The very existence of CAR, Section 6.11, is recognition that the airworthiness standards will undergo a continual process of revisipn and improvement as years pass. To ignore the effects of compounded design changes on basic type design would be &ntrary to the objectives of this section. k. A review of the extent of investigation of compliance with regula- tions shows that the modifications to the rotor and drive system involved endurance testing as well as a complete vibratory stress investigation. Performance changes resulting from the increased power were cause for a substantially complete flight performance investigation. The weight changes involved*required a substan- tially new structural substantiation program. 4. CONCLUSIONS a. Based upon these facts, it is concluded that the original approval of the design changes included in the modification kit did entail a substantially complete investigation. b. In consideration of the foregoing, it is found that Bell Helicopter Company has not shown that the provisions of the 6.11(e)(3) are not applicable, nor has it shown that the proper level of safety would be provided by an interpretation of Section 6.11(e)(3) which would permit the proposed kit of changes to be eligible for approval under the regulations originally applied to the Model 47G-2 helicopter. Page 10 Chap 3 Par 3 6 Jan 71 l b REVIEW CASE NO. 2. BOEING 707-100 SERIES, SR-422 VERSL'SSR-422B - LANDING CLIMB REQUIREMENTS (Issued 11 June 1963) 1. 1NTRODUC';‘lON .--- The Boeing 707-100 series airplanes dre certificated under the per- formance requirements 02 5R-422. In comparing the all-engine- oper,ati.rg hAding c!;ab require~nt, 423.219, of SR.-422 with the corresponding but !ater recuiremerts of SR-422B, The Boeing Company noted that the rrql.\.il:ed climb gradLent has been reduced from 4.0 percent in 5X-422 to 3.2 percent in SR-422B. l3c:eb-q states that the higher climb gradient requirement of SR-427. resuits in a severe economic penalty for .airJ.jne operations at high-a!tKi.tide airports such as Denver, Colorado. In 9rder to increase the meX!.:,!3m 0 esacing P landing wei,ght at high-altitude airports under SR-422, Boeing used an alternate reduced landing flap po eition of 30 degrees which gave higher climb performance hilt resulted in i.ncreased brake and tire wear, as well as longer landing distances, Boeing believes that the I+.0 percent climb requirement of 5X-422 unjustly requires a higher level. of safety than the later req.uirements of SR-42213, and results in a severe economic penalty when compared to other model. jet transport airplanes which are certificated under SR-422B requirements. Roe ing , therefore, requests that the landing c!imb gradxent requirement for the Model 707-100 series airplanes be reduced to 3.2 percent as in SF-422B while remaining undeir the rest of the perfornarxe requjrements of SR-422 in other respects. a . Boeinr letter 0E December --A 1961 to the ;&stern Region 28, --..---..---hl- This letter introduced Boeing's request and presented the reasons and justification. b. WE-2iO letter: of January 8, 1962, to Boeing ------.- -1 This letter acknowledged Boeing's letter of December 28, 1961, and stated that Boeing's request was beI.ng svaluated.‘ C. WE-210 memorandum of January 31, 1962, to FS-100 This memorandum contains a repetition of Boeing's request and presentation, together with copies of the pertinent correspond- ence between Boeing and the Western Region. WE-210 concluded that Boeing's request could not be granted without the issuance of an FAA exemption, and requested our early concurrence with their stand and whatever comments we had on the subject Chap 3 Par 1 Page 11 8110.6 6 Jan 71 d. WE-210 memorandum of February 27, 1962, to FS-100 / This memorandum directed our attention to WE-210's memorandum of January 31, 1962, (item C above), for which WE-210 desired an early reply due to a Boeing request. e. FS-iO0 memorandum of March 15, 1962, to WE-210 This lllemorandum acknowledged WE-210's memorandums of January 31, 1962, and February 27, 1962, and informed the Regional Office that Boeing's request would be processed as an Engineering and Manufacturing Division Review Case over FS-l's signature. 3. FACTS IN THE CASE a. A comparison of the required landing climb gradient in the SR-422 series of regulations is as follows: . Re$,ulanion Required Landing Climb Gradient SR-422 4.0 percent SR-422A 3.2 percent SR-422B 3.2 percent b, The above table shows that the required landing climb gradient for SR-422A and SR-422B is the same. This point is emphasized in order to establish the intent of the regulations regarding mixing of regulations for type certification purposes. The preamble of SR-422A in the fourth paragraph of the first page clearly states, with respect to the use of portions of SR-422A instead of the entire SR-422 regulations, that it is intended that compliance be shown with all the provisions of SR-422A if used, and it is not intended to Git a showing of compliance with some portions of SR-422A and different portions of SR-422 simultaneously. The same principle would apply to mixing of SR-422B and SR-422 regulations. c. The following is a direct quotation from the preamble of SR-422A of the portion concerning the mixing of SR-422A and SR-422: ‘1 . . . . it is intended that compliance be shown with all the provisions of this regulation and it is not intended to permit a showing of compliance with portions of this regulation and portions of SR-422." Page 12 Chap 3 Par 2 -‘ 0 6 San 71 l - REVIEJW CASE NO. 3. REQUEST BY FOR RUDDER ATRPLA.?X? 1. INTRODUCTION --.-- / DOUGL4S AIRCRAFT CC'MPANY PEDAL NGSEWHEEL STEERING (Iss'.;ed 11 June 1963) a. The Douglas Aircraft Company has incorporated a rudder pedal steer- 8110.6 FOR CREDIT ON DC-8 ing system on the DC-8 series aircraft which provides nosewheel steering through the rudder pedals. This is a desirable design feature, not incorporated at this time on any other transport air- craft, in that it improves directional control with no additional effort on the part of the pilot for all ground operations including takeoffs, landings, and taxiing on dry, wet, or slippery runways, and in high winds. b. Douglas has requested that credit, in the form of lower critical engine failure speeds, be given the DC-8 airplanes incorporating this design feature. 2. CHRONOLOGICAL HISTCRY- -.--- a. Douglas Aircraft Company letter dated October 21, 1960, to the Director, Flight Standards Service, requesting exemption for DC-8 aircraft from that portion of SR-422B, paragraph 4T.l14(a), which requires that the critical engine failure speed Vl be determined with primary aerodynamic controls alone. b. Meeting held in Washington on October 27, 1960, by representatives of the FAA Washington Safety Regulations Division, EngineerFng and Manufacturing Division, FAA Western Region Flight Test Section, and the Douglas Aircraft Company to discuss the Douglas petition for exemption. c. Letter from the Chief of the Regulations Staff, FAA, Washington, dated December 1, 1960, to the Douglas Aircraft Company advised that their petition for exemption had been reviewed and suggested that the Douglas proposal may be approved under the equivalent safety provisions of CAR 4b.10. This letter also advised Douglas that the request for petition had been referred to the Washington Office of the Engineering and Manufactur.n, 4 n Division for cechnica? evaluation under Section 4b.10. d. F&A Western Region Flight Test Section memo-randurn ta FAA Washington Flight Test Branch dated June 14, 1961, advised that Douglas was currently submitting a revised proposal to demonstrate critical engine failure speeds V 1 with active rudder pedal steering. Chap 3 Par 1 1 Page 1.5 8110. 6 6 Jan 71 e. Douglas letter dated June 20, 1961, to the FAA Engineering and Manufacturing Division submitted the following proposal for deter- mination of speeds for the DC-8 series 50 airplanes under equiva- lent safety provisions of CAR 4b.10: "Douglas Aircraft Company hereby requests that the V,, for the DC-8 series 50 airplanes be certified under tieF equivalent level of safety provisions of CAR 4b.10. It is proposed to certify the V with rudder pedal nose- gear steering connected undeFcget runway conditions using elevator control up to the limit of one-hand con- trol capability. IL has been shown during these demon- strations that the resulting Vmcg provides a level of safety equal to or greater than that attained without the use of the rudder pedal nosegear steering system on both wet and dry runways. It is proposed to use this demonstrated Vmcg for all takeoff conditions when no ice, snow, or slugh exists on the runway; at ambient air tem- peratures above 40°F. with or without precipitation and at any temperature when no ice, snow, or slush exists on the runway and no precipitation is present. For takeoff conditions with ice, snow, or slush on the runway, or with visible precipit<ition and temperatures below 40°F., it is proposed to use V,,g as demonstrated under existing SR-422B regulations and interpretations." f. FAA Washington Engineering and Manufacturing Division letter dated June 30, 1961, to Douglas Aircraft Company advised that their pro- posal had been reviewed and that the FAA Western Kegion would advise Douglas of the FAA decision. g. FAA Washington Engineering and Manufacturing Division memorandum dated July 7, 1961, to the FAA Western Region Flight Standards Field Division advised the criteria under which the Douglas pro- posal would be acceptable. These criteria are as follows: (1) The minimum V, speed tested with rudder pedal nosegear steering connect& wit11 nosewheel noticeably light on wet runway. These minimum Vl speeds may be used operationally for takeoff conditions as follms: (a) At all ambient air temperatures on a dry runway (b) At ambient air temperatures above 40 degrees Fahrenheit on a dry or wei runway (which means no ice, snow, or slush) Page 16 Chap 3 Par 2 d a d a ’r t” 6 Jan 71 8110. 6 (2: The minimum Vl speed teeted with primary aerodynamic controls alone. These minimum Vl p 8 eeds must be used operationally for takeoff conditions as follows: (a) When there is ice, snow, or slush on the runway (b) At ambient air temperatures below 40 degrees Fahrenheit with precipitation (3) Airplane Flight Manual The airplane flight manual should clearly describe to the pilot when, and under what circumstances, the various ground minimum control speeds are applicable. In addition, the manual material should indicate very plainly that all of the accelerate-stop distances are still based on dry conditions in accordance with past practice. h. FAA Western Region Engineering and Manufacturing Branch letter dated July 1, 1961, which transmitted to Douglas the criteria for approval of the rudder pedal steering credit for the DC-8 aircraft. 1. Dougias letter dated January 2, 1962, to FAA Western Region Engineering Branch submitted the following revised proposal for rudder pedal steering credit in determining ground minimum con- trol speeds for DC-8 aircraft: Runway Surface Ambient Air Applicable Vmcg Curve of Elevator Control Condition Temperature -- DC8-Al.2, 516E Force Required Dry All Temperatures B 0 Wet Above 40 Degrees B 20 lbs. to 25 lbs. Fahrenheit (push) We t 40 Degrees Fahrenheit or less A 0 Snow, All temperatures A 0 slush or ice Chap 3 Par 2 Page 17 8110.6 6 Jan 71 j. FAA Western Region Flight Test Section memorandum dated January 8, 1962, transmitted the revised Douglas proposal (i above) together with Douglas substantiating data to FAA Washington Flight Test Branch. 3. FACTS IN THE CASE a. The current airworthiness requirements, Special Regulation 422B, Section 4T.l14(a), requires that the critical engine failure Vl be "not less than the minimum speed :lt which controllability by primary aerodynamic controls alone is demonstrated during the takeoff run to be adequate to peGit proceeding safely with the takeoff using average piloting skill, when the critical engine is suddenly inoperative." b. The currently approved critical engine failure speeds for the DC-8 series aircraft were established by test with the rudder pedal steering disconnected and the nosewheel noticeably light on the runway, to simulate the slippery runway conditions envisi.oned by SR-42213, Section 4T.l14(a). Douglas proposes in their January 2 proposal, to retain those speeds for wet runways when temperatures are at or below 40 degrees Fahrenheit (4.5C) and on snow, slush, and ice-covered runways at all temperatures. C. The January 2 Douglas proposal also requests approval of additional critical engine failure speeds, V,, for wet runways when temper- atures are above 40 degrees Fahrenheit (4.5C) and for dry runways at all temperatures. These speeds were obtained by testing on a wet runway with rudder pedal steering connected and with 20-25 pounds of forward pressure on the elevator control. The proposed speeds correspond to those obtained by tests on a dry runway with zero elevator force and with rudder pedal steering connected. d. The DC-8 rudder pedal steering is controlled by, ihc rudder pedals and is, therefore, always active whenever the pilot applies rudder (primary directional aerodynamic control) for directional control. Full rudder deflection and rudder pedal steering are attainable with approximately 70 pounds of rudder pedal force. e. The 20-25 pounds of elevator force results in a nosegear strut condition which is quite light as shown by report DC-8 A12.525. A 20-pound push force results in a nosegear shock strut compres- sion from one to five inches. The total strut travel for full,. compression is 16 inches. Therefore, the nosewheel is noticeably light on the runway when the 20-25 pounds of elevator for;e is applied. “a Page 18 Chap 3 Par 3 -0 6 Jan II 8110.6 During FAA and Douglas testing with instrumented test aircraft, it has been shown that a push force of approximately 15 pounds was a normal pilot reaction in controlling the airplane following an engine failure. During these tests, the pilot was not aware that he was applying a push force. The nosegear strut compression varied between zero to six inches. f. The Douglas Aircraft Company has been training all operators of the DC-g aircraft to apply a push force to the elevator control for all takeoffs. It has been verified that airlines are train- ing their DC-3 pilots to apply a push force during all takeoffs. g. It has been found that the critical engine failure speeds, Vl, proposed by Douglas in their letter dated January 2, 1962, to the FAA Western Region Engineering and Manufacturing Branch, were deter- mined.in 'accordance with the criteria contained in the letter dated July 7, 1961, from the Washington Chief of the Engineering and Manufacturing Division to the Chief of the Flight Standards Field Division, Western Region, and FAA test pilots have found that the speeds can be realized in service by pilots of average skill. FAA test pilots also feel that the rudder pedal steering is a very desirable design feature and that credit should be given when incor- porated on any transport design. h. The proposed airplane flight manual procedures clearly describe con- ditions under which the various critical engine failure speeds are applicable. Although all manuals state that takeoff and landing performance is based on dry runways, the proposed manual emphasizes that accelerate-stop distances are based on a dry runway condition. The airplane flight manual procedures also inform the pilot that increased forward pressure on the elevator control will pro-lride increasingly effective directional con:::01 on the ground. The appli- cable portions of the flight manual are quoted below: IN THE LIMITATIONS SECTION: Engine Failure Durin_t Takeoff - - -.-- - .- - _.-... "DuZing takeoff, monitor desired takeoff EPi( and observe Vl, V and ‘J2 speeds. The noszwheel s!lould remain Eirmly in ckir.act l&th the suaw:i;~ until '1, is obtained, . . .'I "The reqofrad t&eoff field length is based on stopping on a dry hard surface runway....." Chap 3 Par 3 Page 19 8110.6 6 Jan 71 There are two types of Vm, g round speeds depending on the runway surface condition presented in this manual. (1) vm,g MT-DRY) V mcg (WET-DRY) is applicable at all temperatures if the runway is dry, and above 4.5C if the runway is wet b,ut free from ice, snow and slush. (2) Vmcg (COLD-WET-ICE) V (COLD-WET-ICE) is applicable if the runway is wgtgat temperatures below 4.5C and at all temper- atures if there is snow, slush or ice on the runway. It is also conservative for all conditions since V,,g (COLD-WET-ICE) is faster than Vmcg (WET-DRY). IN TKE PERFORMANCE SECTION: Effect of Rudder Pedal Nosewheel Steering on V,, "The rudder pedal nosewheel steering feature on the DC-8 provides a reduction in V for all runway surface con- ditions from the V,,, ava!% ble with aerodynamic rudder control only. The e B fectiveness of rudder pedal nosewheel steering can be improved by applying a push force on the control column." Page 20 Performance data is shown in this manual for two levels of Vmcg* These are: Cl) vm, (WET-DRY) for use in determining takeoff per + rmance on wet runways which are free from ice,1 snow and slush at temperatures above 4.5'C and pn dry runways at all temper.atures. The vmcg's presented for these conditions, V,,, (WET-DRY), are those obtained with rudder pedal nosewheel steering operating on wet runways, using normal pilot tech- Wuf , with a positive push force on the control column. q2) vm, B (COLD-WET-ICE) for use in determining takeoff per ormance on wet runways at temperatures of 4.5OC and below and on snow, slush and ice-covered runways at all temperatures. The vmcg (COLD-WET-ICE) shown for snow, slush and ice conditions have not incorpor- ated the benefit available due to rudder pedal nose- wheel st:eering. . Chap 3 Par 3 - a . . . . 6 .Pan 7 I 8110. 6 LX\ connid~eration of the foregoing, it has been found that, under the conditions for which Douglas is requesting approval, the rudder pedal steering i,a a compensating feature which results in a level of safety cqklivalenr: to that required by Special Regulation No. SR-42233, Section LT'.11,4(a). Therefore, the Douglas request is granted under the equivalent safety provisions of CAR 4b.10. Page Zl(and 22) 6 Jan 71 8110.. 6 l W REVIEW CASE NO. 4 NORTH AMERICAN AVIATION REQUEST FOR ISSUANCE OF NA-265 TYPE CERTIFICATE-WITH DATA SHEET LIMITATIONS OR AIJTHORIZATION FOR HORIZONTAL STABILIZER SHORT-TIME REPLACEMENT (Issued 17 July 1963) 1. 2. l ,W INTRODUCTION. North American Aviation has requested the Western Region to issue the type certificate for the NA-265 with special inspection and repair procedure limitations indicated on the type certificate data sheet. The request stems from failures of the horizontal stabilizer skin and ribs which have occurred during flight testing. The Western Region contends that the type design should contain no known adverse or undesirable feattrc at the time of issuance of the type certificate. As an alternate request, North American may, under the fatigue strength requirements of Part 4b of the Civil Air Regulations, Section 4b.270(a), propose replacement of the skin and ribs after loo-300 hours of flight. The Western Region contends that such periods appear unreasonably low for the airplane and the user in question. CHRONOLOGICAL HISTORY. a. The Western Region is evaluating the type design for the North American Model 265. Procurement of this aircraft by the United States Air Force is contingent on Federal Aviation Agency type certification under Part 4b. In showing compliance with CAR, Part 4b, the applicant elected to conduct a fatigue evaluation of this aircraft in accordance with Section 4b.270(a). He selected a target aircraft service life of 10,000 hours. b. The Western Region reported, in a telegram, WE-210 January 301955, that cracks had been found in the horizontal stabilizer skin and ribs. These cracks occurred in all five test aircraft during the flight test program conducted to date. Special inspections and repairs were imposed to keep cracks within reasonable safe limits during the remainder of the FAA certification program. The cause of the cracking has not been identified but acoustical fatigue is considered one possible contributing factor. C. The following additional information was provided in a telephone conversation with the Western Region on February 7: (1) Thirty-six aircraft have been delivered to date to the Air Force. The Air Force has instituted a mandatory special inspection of the stabilizers beginning after the first 40 hours of flight, and after each subsequent 100 hours of flight. The results of this inspection are not yet available. Chap 3 Par 1 Page 23 8110.6 6 Jan 71 (2) Among four flight test aircraft on which stabilizer cracks have been reported, the installation of new stabilizers has been necessary after 100-200 hours on two separate occasions. One aircraft has been found to have two stabilizer cracks after 430 hours, another has been found to have nine stabilizer cracks after 256 hours, and a third has been found to have 17 stabilizer cracks after 260 hours. 3. FACTS IN THE CASE. a. The current airworthiness requirements, CAR, Part 4b.300, state that "The airplane shall not incorporate design features or details which experience has shown to be hazardous or unreliable." This requirement dictates that a type certificate should not be issued under the proposed conditions until a thorough evaluation has been completed on the modified horizontal stabilizer design. It is equally unreasonable to issue a type certificate for a design where findings prior to the issuance establish that an FAA airworthiness directive (AD) will be needed shortly after type certification, or where a limitation on the type certificate data sheet is to be incorporated, which is tantamount to an AD. b. In showing compliance with CAR, Part 4b.270(a), it is incumbent' on the applicant to have selected a reasonable target life early in the design program, and evaluate the design against this figure, taking into account the provisions of CAR, Part 4b.270(a)(l), and the recommendations of Section 1 of Appendix H to CAR 4b. Based on rthe'adverse experience to date, it is highly doubtful the applicant has established proper correlation with the typical loading spectra expected in service, particularly if he now can only substantiate a 100-300 hour replacement period - an unreasonably low period compared with the target life of 10,000 hours originally selected. C. CAR, Part 4b.270(a), requires that "The structure shall be shown by analysis and/or tests to be capable of withstanding the repeated loads of variable magnitude expected in service," Our oral understanding is that the applicant will contend that the loading spectrum encountered in flight tests conducted to date is more severe than that expected in normal transport use, and therefore that the 100-300 hour point of severe cracking is unduly conservative. However, the intended Air Force usage includes training missions. The severity and frequency of loads experienced in these training missions is expected to equal or exceed those encountered in flight testing. Page..24 Chap 3 Par 3 h ,Tan 7 1 ,811O. 6' l ili cc. tl . Sfsction 306 of the Federal Aviation Act of 1958 states, "In exercising, the authority granted in and discharging the duties . -i:npos:,d hy this Act, the Administrator shall give full considera- t i or! to the requirements of national defense, and of commercial :ind g<:neral aviation, and to the public right of freedom of transit through the navigable airspace." Since the United States Air Force is procuring these aircraft, it is not in the best interest of national defense for the FAA to certificate this aircraft as proposed. CONCLUSIONS. consi.deration of the foregoing, it is concluded under the provisions Part 4b of the Civil Air Regulations, Section 4b.300, that: issuance of a type certificate under Part 4b of the Civil Air Regulations shall be withheld for the North American NA-265 aircraft incorporating the present horizontal stabilizer design, an d prior to granting a type certificate under Part 4b of the Civil Air Regulations for the North American NA-265, the applicant must substantiate the reliability of the redesigned horizontal stabilizer. The substantiation of the redesigned horizontal stabilizer shall include: v a. accurate identification of the cause of the cracking and incor- poration of this factor in the loading spectrum, b. conduct of the complete NA-265 functioning and relj.ability test program with the redesigned horizontal stabilizer installed, c. jn lieu of item "b," conduct of a ground test on the redesigned horizontal stabilizer wherein the loading spectrum determined in i-tern !'a" is simulated for flight time corresponding to the total flight time utilized by the applicant and the Federal Aviation Agency in showing compliance with the flight require- ments of subpart B of the Civil Air Regulations plus the flight time original.T.y specified for the NA-265 functioning and reliability test program; in addition, at least 25 hours of actual flight time with the redesigned horizontal stabilizer installed, shall be satisfactorily completed. Chap 3 Par 4 f Page 25(and 26) 6 Jan 71 8110.6 REVIEW CASE NO. 5 DOUGLAS AIRCRAFT COMPANY REQUEST FOR AN INTER- PRETATION OF CIVIL AIR REGULATIONS 4b.260 AND 4b.350(e) RELATIVE TO TYPE CERTIFICATION OF THE DC-8F (Issued 17 July 1963) 1. INTRODUCTION. The Douglas Aircraft Company, Incorporated, has requested a ruling from the Flight Standards Service for their DC-8F combination cargo- passenger configuration as to whether or not an aisle must be maintained from the flight compartment to the passenger compartment after the aircraft has experienced the crash loading conditions specified in Civil Air Regulation 413.260, Emergency Landing Conditions - General. Their request also asks for confirmation that accessibility to the door specified by CAR 4b.3SO(ej, Pilot Compartment - General, is only required under normal flight and ground loading conditions but not under the emergency landing conditions specified in CAR 4b.260. The Western Region Engineering and Manufacturing Branch concurs with the statement of the problem and also has requested policy guidance on the case. 2. CHRONOLOGICAL HISTORY. 2 , Mr. George Castle, Douglas Aircraft Company, FAA Liaison Engineer, outlined the problem to representatives of the Washington Engineering and Manufacturing Division on December 6, 1961. He pointed out that the question has arisen because of the unique nature of the Douglas DC-8F configuration wherein the cargo compartment separates the pilot compartment from the aft located passenger compartment. h. Western Region representatives confirmed the need for a policy ruling on the matter during visits to the Washington Office on December 6, 1961, and again in February 1962. C. Mr. George Castle, Douglas Aircraft Company, Incorporated, re- quested confirmation of the FAA ruling on the matter in a wire to the Director, Flight Standards Service, on February 21, 1962. d. The Director, Flight Standards Service, wired Douglas Aircraft Company, Incorporated, on February 23, 1962, that the matter was under study and a reply would be forthcoming by February 28, 1962. e. Western Region representatives confirmed on February 27, 1962, that: (1) The tiedown means for cargo retention are designed to withstand the 1.5g side loading condition specified in CAR 4b.260. Chap 3 Par 1 Page 27 8490.6 6 Jan 71 f. h. i. Page 28 (2) The crash net separating the pilot compartment and the cargo compartment would be designed to account for the 9g forward crash load condition specified in CAR 4b.260, and that the dynamic effects associated with cargo move- ment would be suitably accounted for. (3) In normal flight and landing the crash net is slack and could be unfastened to gain access to the cargo area through an aisleway consisting of the outer fuselage ehell and cargo loading restrictions. (4) Under a crash condition the net is loaded, thu precluding unfastening of the net, (5) The dislocation of the cargo and resulting structural deformation during a survivable crash would be such that the aisleway provided and maintained under normal flight and landing to gain access to the passenger compartment, would be blocked, thus precluding access by a flight crew member to the passenger compartment. Mr. L. J. Devlin, Vice President - Director, Engineering and Product Development, Douglas Aircraft Company, Incorporated, wrote to the Director, Flight Standards Service, on March 29, 1962. Mr. Devlin expressed concern about the problem of a ruling being established regarding the aisle.. He requested an opportunity to dimuss the subject with the Director, should an unfavorable ruling be made. The Director, Flight Standards Service, wired the Western' Region on April 30, 1962, that an aisle between the flight compartment and passenger compartment must be maintained subsequent to load factor conditions of CAR 4b.260. The Chief, Engineering and Manufacturing Branch, Western Region, transmitted the conclusion requiring an aisle be maintained after crash loads to the Chief Engineer, Douglas Aircraft Company, Inc. in a letter dated May 8, 1962. 14essre. Strang, Castle, and Adams met with personnel of the Flight Standards Service on May 23, 1962, and presented and discussed their objection to the conclusion that an aisle must be maintained. They were requested to resubmit their case, including technical, economFc p and other aspects discussed during the meeting. It was agreed that a resubmittal of all factors would be forwarded from Douglas Aircraft Company in the immediate future, Chap 3 , Par 2 6 Jia 71 8110. 6, ‘kb.&cwl ‘Ladl j. Mr. I,. J. Devlin, forwarded to the Director, Flight Standards Service, on July 17, 1962, a report entitled '"Post-Crash Crew- Passenger Compartment Aisle Probability Study" for Model DC-8F. A reevaluation of all aspects of adequate provisions for passenger evacuation was carefully considered. 3. FACTS IN THE CASE. a. The crash barrier between the pilot compartment and the cargo com- partment, and the restraint provisions for cargo carried in the compartment will be designed to comply with applicable strength provisions of CAR 4b.260, Emergency Landing Conditions - General, and CAR 4b.359, Cargo and Baggage Compartments, respectively, as outlined in the FS-100 letter of October 24, 1961, to the Douglas Aircraft Company and the FS-100 memorandum of Octoberl2, 1961, to the Western Region. b. Means exist, under normal flight and ground conditions, whereby the flight crew can gain access through the crash barrier and cargo compartment to the passenger compartment. This is accomplished by unfastening detachable portions of the barrier. C. The passenger comp;lrtment will comply with the provisions of CAR 4b.362, Emergency Evacuation. d. The CAR 40 operating rules, and in particular, CAR 4-0.265, Flight Attendant, require that at least one flight attendant be provided by the air carrier on all flights carrying passengers in airplanes of ten-passenger capacity or more. e. The CAR 41, 42, and 43 operating rules, do not contain a provision similar to that provided in CAR 40.265. f. Douglas Aircraft Company, Inc., Report Number SM-22611, "DC-8 Flotation Study," revised July 18, 1961, was checked and approved by the Western Region and submitted as requested to the Washington Office for additional review. This review has indicated no fallacies in the ditching analysis. 4. CONCLUSIONS. In consideration of this request, it is unnecessary that the Douglas Aircraft Company provide flight crew access to the passenger compartment on the DC-8F as implied in CAR 4b.350(e) after the airplane has ex- perienced the emergency 1andi:lg conditions of CAR 4b.260 providing: a. Means exist, under normal flight conditions, whereby the flight crew can gain access to ti;e passenger compartment. Chap 3 Par 3 page 29 8110.6 . i. 6 Jan 71 b. The crew and passenger areas comply with the provisions cef CAR 4b.362 with respect to emergency evacuation. c. At least one flight attendant be required for CAR 40, 41, 42, and 43 operations. The attendant should be trained and have demon- strated ability to perform all emergency functions, including ditching, The Airplane Flight Manual is to include complete in- formation pertaining to these procedures. Page 30 Chap 3 Par 4 6 Jan 71 8110. 6 REVIEW CASE NO. 6 GRUMMAN AIRCRAFT ENGINEERING CORPORATION REQUEST TO INCREASE THE MAXIMUM PASSENGER CAPACITY OF THE MODEL G-159 FROM 19 TO 24 PASSENGERS (Issued 17 ..Iuly 1963) 1. INTRODUCTION. The Grumman Aircraft Engineering Corporation has requested the Eastern Region to approve an increase in the maximum passenger capacity of their Model G-159 from 19 to 24 passengers. As compensation under the provision of Civil Air Regulations 4b.362(c)(4) for an increase of five passengers, Grumman requests approval to activate the 20-inch by 36-inch floor level cargo door located in the aft right side of the fuselage as a passenger exit. Grumman also proposes to install an evacuation slide on this exit. The Eastern Region contends this exit (Type III dimensions) and the presence of the left forward entrance door (air stair) are sufficient compensation to allow an increase of five passengers, and requests Washington Office concurrence. 2. CHRONOLOGICAL HISTORY. a. The Grumman G-159 was type certificated by the Eastern' Region as a 19-passenger aircraft. The emergency exit aspects'were approved on the basis of CAR 4b.10, Eligibility for Type Certificates, as being equivalent to the provisions of CAR 4b.362, Emergency Evacuation, as amended by Amendment 4b-5, effective April 9, 1957. The emergency exit provisions included two pairs of 19 inches by 26 inches elliptically shaped overwing exits and an overhead hatch aft of the crew compartment. Additional.openings provided but not considered as emergency exits are: a main entrance air stair door on the left forward side and a rectangular floor level cargo door (20 inches by 36 inches) opening on the right rear side. b. Under CAR 4b, Amendment 4b-5, for 19 passengers, one pair of Type III exits, plus crew escapement means, was needed. Under the provisions of CAR 4b,362(c)(3) Grumman elected to substitute two pairs of Type IV exits in lieu of the required one pair of Type III exits. These Type IV exits were elliptical with a major horizontal axis of 26 inches, and a minor vertical axis of 19 inches. Under the provisions of CAR 4b,362(b)(4) Type IV openings are required to be rectangular and not less than 19 inches wide and 26 inches high. C. Under the provisions of CAR 4b.10, Grumman was required to conduct an evacuation test to establish if the two elliptical exits on each side were reasonably equivalent to one Type III exit on each side. The tests conducted on July l?, 1957, and duly witnessed by the Civil Aeronautics Administration at that time, demonstrated this. Chap 3 Par 1 Page 31 8110.6 6 Jan 71 The installation was subsequently approved by the Eastern Kegion and formed the basis for showing equivallence under CAR 4b.10 with CAR 4b.362(c)(l) in the type certification of the Grumman G-159 as a 19-passenger configuration. d. Early in 1961, Grunrman requested approval from the Eastern Region to increase the capacity of the G-159 from 19 to 29 passengers. Under CAR 4b.362(c)(4), Grumman requested consideration of the presence of the right rear aft cargo access door and the left forward air stair door as compensating factors. The Eastern Region requested a Washington ruling on this in their memorandum of May 15, 1961. A refusal of the Grumman request was forwarded to the Eastern Region in the Washington reply of June 13, 1961, and subsequently conveyed to Grumman by the Eastern Region. The basis 92s as follows: The table in CAR 4b,362(c)(l) requires for 20 to 39 passengers at least one Type II and one Type IV exit per Lb,:!?. ‘Cl-a G-159 has en the left side two exits which Grumman has shown to be equivalent to Type IV exits; one more such exit than required is provided. The main entrance door, however, which contains the air stair was not considered to qualify as an emergency exit due to the mechanical, hydraulic, and electrical complexity of the stair mechanism. On the right side of the fuselage, the 20 inches by 36 inches cargo door fell short of the Type II exit dimension required by CAR 4b,362(c)(l). Therefore, it was concluded that insufficient compensating factors existed to authorize an increase in passenger seating capacity to the maximum of ten permitted under CAR 4b.362(c)(4). e. Under CAR 4b.362(~)(4), Grumman has recently reapplied to the Eastern Region :for approval to increase the passenger seating capacity from 14 to 24 passengers as stated in the introduction.' The Eastern Region believes th e request is reasonable and in their memorandum of January 29, 1962, has asked for 'Washington: approval.. 3. FACTS IN 'THE CASE. a. The 24-passenger version complies with CAR 4b,362(a) with respect to a top hatch for crew escapement. b. The 24-passenger version exceeds CAR 4b.362(c)(l) with respect to the required one pdir of Type I'd exits on each side as two pairs are provided on each side. Page 32 Chap 3 P&r 2 b Jan I1 8110.6 // I ,/‘. 1*J,l C. The 24-passenger version requires a pair of Type II emergency exits as specified in CAR 4b,362(c)(l). These do not exist, but the authority vested to the Administrator in CAR 4b.362(c)(4) clearly permits approval of an increase in passenger seating capacity up to ten passengers irrespective of CAR 4b.362(c)(l), providing compen- sating factors in the emergency evacuation means exist. Each side of the aircraft, right and left, must be considered before con- cluding what, if any, compensating factors are present. For the right side of the aircraft, the presence of a third opening, heretofore not considered for emergency evacuation, is a compensating factor. As herein considered, it is intended that as many as ten additional occupants may be authorized with the addition of an exit of reasonably high effectiveness and that a lesser number of occupants would be authorized with the addition of a less effective exit. The effectiveness of the additional exit varies with para- meters such as: the type, location, and number. The presence of an aft opening, at floor level, and of Type III dimensions (20 inches by 36 inches); the proximity of the last two rows of seats to this exit; the presence of an unobstructed passageway at least 20 inches wide; and the fact that this opening is a third means of egress on the right side of the aircraft, or 50 percent more than the number required, clearly establishes that the exit is an effective means of evacuation. Assuming evacuation is through the right side exits, it is reasonable to increase the passenger seating capacity by five additional persons. For the left side, we do not consider there are compensating factors present in the emergency evacuation means now provided. There is an additional exit of Type I dimensions which incorporates an air stair door, but this door is not considered acceptable for emergency evacuation (Reference - Item 4, Chronological History). One alter- native is for the applicant to qualify the present air stair door at least as a Type II emergency exit as defined in CAR 4b.362(b)(2). This would entail removal of the air stair door and installation of a conventional side hinged door. With this modification, the left side of the airplane would exceed the present minimum requirements specified in CAR 4b.362(c)(l) such that it would be reasonable to increase the passenger seating capacity by five additional persons. d. The evacuation slide as proposed by Grumman at the 20-inch by 36- inch aft cargo opening is not required under the provisions of CAR 4b.362(e)(7) as the exit is less than six feet from the ground. 4. CONCLUSIONS. In consideration of the foregoing, it is concluded that the Grumman Aircraft Company's request to increase the passenger capacity on their Page 33 8110. 6 i 6 Jan 71 Model G-159 from 19 to 24 passengers, is acceptable under the compen- sating factor provisions of 4b,362(c)(4), providing: a. b. C. d. The door located in the aft rear side of the fuselage complies with the emergency exit arrangement, marking, and Access provi- sions of CAR 4b.362(e), (f), and (g), respectively. The cargo and baggage compartment in the aft portion of the fuselage and immediately adjacent to the right rear exit complies with the provisions of CAR 4b.260, Emergency Landing Conditions, and CAR 413.359, Cargo and Baggage Compartments. The passageway leading to the rear exit on the right side is unobstructed and not less than 20 inches wide. The forward main entrance door on the left side of the fuselage is suitably modified to qualify at least as a Type II emergency exit as defined in CAR 4b,362(b)(2). Page 34 Chap 3 Par 4 6 Jm 71 8110.6 REVIEW CASE NO. 7. SIKORSKY AIRCRAFT REQUEST TO DELETE THE CURRENT SERVICE LIFE LIMITATION ON THE MODEL S-58 MAIN ROTOR BLADE AND CUFF, TO USE A BLADE INSPECTION METHOD (BIM) TO INDICATE SERVICEABILITY OF THE BLADES, AND TO HAVE UNLIMITED SERVICE LIFE ON THE CUFF, PREDICATED ON VISUAL INSPECTION (Issued i7 July 1963) 7 I. INTRODUCTION. Sikorsky Aircraft has requested approval from the Eastern Region .to eliminate the mandatory lOOO-hour life limitation on the Model S-58 main rotor blade when the blade is equipped with a blade)inspection method (RIM), which consists of pressurizing the hollow spar. With RIM incorporated, Sikorsky contends the main rotor blades may be used indefinitely and only blades found unserviceable for further use need be discarded. Sikorsky has also requested approval from the Eastern Region to eliminate the mandatory service life of the Model S-58 main rotor blade cuff, which constitutes the b&de attachment fitting, predicated on visual inspection only. The Eastern Region is of the opinion that the BIM installation on the main rotor blade will provide a level of safety equivalent to that obtained under CAR, Part 6.250, Main Rotor Structure, provided that the inspection interval and the reliability of the method in service are satisfactorily substantiated. With respect to elimination of the mandatory service life on the cuff attachment, the Eastern Region contends that the present service life should be retained since visual inspection alone will not suffice. 2. -CHRONOLOGICAL HISTORY. a. July 27, 1960 - A fatal accident of the S-58 occurred in aivil operation at Chicago, Illinois. b. July 29, 1960 - A telegraphic airworthiness directive was issued reducing tbe service life to 1400 hours on the blade and requiring daily X-ray inspections of all blades with more than 1000 hours' time in service. C. August 2, 1960 - At Fort Rucker, Alabama, a blade fracture was discovered during ground inspection of an Army H-34 after approximately 830 hours' time in service. d. August 3, 1960 - A telegraphic airworthiness directive was issued amending the directive dated July 29, 1960. This latter airworthi- ness directive further reduced the service life to 1000 hours on the blade and required a one-time X-ray of the rotor blade spar. This directive was subsequently printed as AD 60-17-3. Chap 3 Par 1 Page 35 8110. 6 6 Jan 71 e. October 18, 1960 - Sikorsky Aircraft Corparation, by letter SE-9813, to FAA, FS-1120, requested approval of the BIM in- stallation in the S-58 helicopter. f. December 23, 1960 - The FAA (FS-1120 letter) granted approval of the BIM installation. This approval did not alter the lOOO-hour retirement life established by AD 60-17-3. g* June 30, 1961 - Sikorsky (letter SE-2442) submitted Sikorsky Engineering Report No. SER758331, Structural Reliability of the S-58 Main Rotor Blade to FS-1120. A copy of the report was subsequently forwarded to FS-120 by FS-1120 memorandum dated August 15, 1961. ' h. November 22, 1961 - A meeting was held at Sikorsky Aircraft. Representatives of the Washington FAA Airframe Branch, Engineering and Manufacturing Division of FAA Eastern Region Airframe and Equipment Branch and Sikorsky attended. The discussions per- tained in part to structural reliability. i. January 10, 1962 - EA-212 memorandum to FS-120 requested our comments and concurrence regarding approval of the BIM installa- tion. They concluded the current lOOO-hour limitation could be deleted and that the blade could be retired on condition with the BIM installed following complete substantiation of the in- spection interval and gage reliability. They also concluded that the service life of the blade cuff attachment could not be pred- icated on visual inspections as proposed by Sikorsky and the present service life of the cuff would remain in effect. ', j. February 19, 1962 - In discussions held with the Navy Department Bureau of Naval Weapons, it was established that the Navy has initiated action to approve the installation of BIM on the military version of the S-58 and considers the main rotor blades to have a life of 3000 hours with BIM installed. 3. FACTS IN THE CASE. a. The BIM blade inspection method consists of pressurizing the hollow spar of each main rotor blade to ten pounds per square inch. The area pressurized includes the blade attachment to the cuff, but excludes a small portion of the blade tip. BIM is desi.gned to permit inspection personnel to ascertain, through a gage at the root end of the blade spar, that pressure is being maintained and thus no crack exists in the spar and its attachment. Inspec- tion of the blade spar pressure is proposed to be accomplished on a preflight basis. Page 36 Chap 3 Par 2 w’a ‘d 0 6 Jan 71 8110. 6 b. The origlnal certificated service life of the S-58 main rotor blade was 2450 hours based on the procedures outlined in Appendix A to Civil Aeronautics Manual 6. C. Investigation of the Chicago accident revealed that the main rotor blade failed as result of fatigue. To determine the cause of this fatigue failure, Sikorsky conducted an evaluation of the effects of preloads (quick starts), various finishes, corrosion, adequacy cf original flight strain survey, and manufacturing processes.' Upon conclusion of this investigation, no positive cause of the failure was found. d. The Army report of the investigation of the Fort Rucker H-34 incident concluded that this fracture was caused by an undetected' nonmetallic inclusion in the spar. To preclude further incidents of this type, refined manufacturing inspection methods were introduced, both at the material supplier and at Sikorsky. 2. Following the investigation as to the cause of the catastrophic failure at Chicago, Illinois, Sikorsky requested approval of the BIM installation on the basis that it would render the main rotor spar a "fail-safe" structure, and thus eliminate the need for the present safe-life limitation of 1000 hours. Substantiation of the BIM installation was provided by Sikorsky Report SER-58331. In this report, probabilistic and statistical concepts were applied to the results of laboratory fatigue tests and flight stress surveys. Factors considered in the analysis included fatigue crack initiation, crack propagation, inspection interval, and reliability of the BIM. Sikorsky concluded that, on the basis of this analysis, installation of the BIN offered an im- provement of 20 to 1 in reliability. Sikorsky further noted that low occurrence fatigue fractures are caused by the random variability of many factors, and therefore contended that installation of the BIM is required to eliminate fractures which cannot be sontrolled without inspection. Samples of such factors include variability in the operating environment and variability in maintenance and overhaul procedures. On the basis of the above report, Sikorsky concludes that main rotor blades equipped with BTM are fail-safe and can be considered serviceable until a crack is detected. f. CAR Part 1.24(a), Service Experience Changes, states in part "when the Administrator finds as a result of service experience an unsafe condition exists . . . the product shall not be operated until the unsafe condition has been corrected **. unless otherwise authorized by the Administrator under specified conditions and limitations, including inspections . ..." The current main rotor Page >37 t3110.6 6 Jan 71 blade retirement life of 1000 hours was imposed as a result of an unsafe condition. The cause of the fatigue failure has not been determined. The installation of BIM cannot correct the unsafe condition, but can establish the basis for permitting operation beyond 1000 hours by mandatory application of reliable inspection procedures. !3. CAR, Part 6.250(a), Main Rotor Structure, requires that "The service life of such parts (i.e., blades, blade attachments, etc.) shall be established by the applicant on the basis of fatigue tests or by other methods found acceptable to the Administrator." The requirement for the establishment of a service life for the main rotor blades is unequivocal. The Sikorsky proposal for, in effect, a fail-safe design and, more importantly, for unlimited service life, is incompatible with this portion of the requirement. h. The portion of CAR, Part 6.250(a), that states "...by other methods found acceptable . ..I' could permit the use of BIM. An acceptable: mel:hod must be one of unquestioned reliability. Since the Decemtler 23, 1960, approval of BIN, service experience with the method has been limited to several sets of blades being flown by one operator. We have been informally advised by Sikorsky that these sets of blades were handmade, and that difficulty has been encountered in sealing the blade during attempts to put the BIM design into production. The adequacy of BIM as a safe indication of blade failure can be evaluated following its use to a more extensive and widespread degree by operators. Until this use is acquired, complete acknowledgment that the method is acceptable from a reliability standpoint cannot be validated. i. Among the BIN reliability substantiations required from the applicant must be included the approval of a process specifica- tion, in accordance with the provisions of CAR, Part 6.302, Fabrication Methods, the clear establishment and definition of inspection intervals and procedures, as required by CAR, Part 6.305, Inspection Provisions, and ,the demonstration of the gage installation reliability, necessitated by CAR, Part 6.601, Functional and Installational Requirements. j. Sikorsky proposes that the rotor blade cuff life limitation be relieved and that the cuff also be retired "on condition" based on visual inspections. As previously indicated in CAR, Part 6.250(a), a service life must be established. Under this provision this proposal is not acceptable. Considering this proposal as a means to permit an extension of service life, dn the basis of visual inspections only, would not be considered Page 38 Chap 3 Par 3 c 0 l b 6 Jan 71 8110.6' adequate . ,An inspection program similar in capability of crack detection to that of the BIM would be necessary. I ‘t. CONCLUSIONS. In consideration of the foregoing, it is concluded that, under the current provisions of CAR, Part 6.250(a): a. approval of unlimited service life on the Model S-58 helicopter main rotor blades and main rotor blade cuffs, based upon, respectively, BIM or visual inspections, cannot be granted, b. the present service life limitation on the Model S-58 helicopter main rotor blade of 1000 hours may be increased to a finite service life, whose magnitude is substantiated by fatigue tests, provided that the following are established and substantiated: (1) reliable mandatory inspection intervals, (2) the reliability and accuracy of the Bill gage under all operating conditions, and (3) an approved process manufacturing specification. 'hd 0 C. the current retirement life on the Model S-58 helicopter main rotor blade cuffs shall be maintained. Chap 3 'Par 4 Page 39(and 40) 6 Jan 71 8110. 6. l ” KEVIEW CASE NO. 8 REQUEST OF BEECH AIRCRAFT CORPORATION FOR REVIEW OF PROPOSED CE-210 PARTICIPATION IN CERTIFICATION OF THE BEECH MODEL H18 AIRCRAFT (Issued 17 July 1963) 1. INTRODUCTION. The Beech Aircraft Corporation has requested,through the medium of personal representation and in writing, review and reconsideration of the Central Region's proposed extent of participation in the certifi- cation program for the Beech Model H18 aircraft. 2. CHRONOLOGICAL HISTORY. a. By letter to the Central Region dated November 6, 1961, the Beech Aircraft Corporation initiated a certification program under the delegation option procedures of Part 410, Regulations of the Administrator, for a new model, H18, which will be the same as the Model G18S except for: revised engine installation; Hartzell 10152-54 propeller blades; consolidation of four inboard metal fuel tanks to two conventional bladder cell tanks; larger wheels and tires on main landing gear; increase in gross weight from 9,700 pounds to 9,900 pounds basic, and from 9,800 pounds to 10,000 pounds with JATO. 0 ‘Ld b. By letter dated November 17, 1961, the Central Region expressed their intent to participate in the Model H18 certification program to the following extent: (1) Airframe and Equipment Section (a) Review the Basic Loads Report for this model. (b) Review structural substantiation of the gross weight increase to 9,900 pounds (10,000 pounds with JATO). (2) Propulsion Section (a) Review portions of the Type Inspection Report, Parts I and II, pertaining to the powerplant installation. (b) Review data or reports demonstrating compliance of the new bladder cells with the applicable portions of the Civil Air Regulations. (c) Make a general inspection of the powerplant installation. (3) wht Test Section (a) Review Part II of the Type Inspection Report for accuracy and for compliance with the Civil Air Regulations. Page 41 8110.6 6 Jan 71 (b) Flight Test personnel will also check one or more flight items to determine accuracy of the data. (4) Manufacturing and Inspection Section (a) Verify that the applicant has conducted a complete conformity inspection of the product presented for type certification. Review applicant's Form ACA-317, Statement of Conformity. (b) Conduct reinspections on one or more areas covered by the Type Inspection Report, Part I. cc> setermine that equipment installed is in agreement with either the aircraft specification or the manufacturer's technical data equipment listing. 3. FACTS IN THE CASE a. Under the delegation option procedures of Part 410, Regulations of the Administrator, the Federal Aviation Agency is required by Section 410.32(a)(2) to verify compliance with standards, rules, and regulations for unconventional designs and/or design features having a significant effect on safety, and to verify that there are no apparent unairworthy features. Under Section 410.32(b)(l), when the manufacturer makes major changes to a type design for which he holds a type certificate, the FAA will verify compliance as considered necessary. b. For an aircraft of conventional design with which the manufacturer has experience, the minimum FAA participation will normally be the following: (1) (2) (3) (4) Airframe and Equipment Section Spot check basic load report and witness at least one major structural test. Propulsion Section Visually inspect the powerplant installation. Flight Test Section Spot check the manufacturer's type inspection report (Part II) by conducting a flight inspection. Manufacturing and Inspection Section Spot check the manufacturer's type inspection report (Part I) by conducting a ground inspection. d a d l Page 42 Chap 3 Par 2 6 San 71 8110.6 4. CONCLUSIONS. a. Rased upon these facts, kt is concluded that the Beech Model H18 is a conventional aircraft having no unique,featdres which would 'warrant detailed examination and review by the Central Region. b. In consideration of the foregoing, it is determined that the Central Region letter of November 17,.1961, to Beech Aircraft Corporation established a verification program in excess of presently established procedures, and that only the minimum participation shown above should be deemed necessary by the FAA Central Region for all sections except the Propulsion Section. The Propulsion Section should participate to the extent originally proposed. Chap 3 Par 4 Page 43(and 44) 6 Jan 71 8110:6 REVIEW CASE NO. 9. DOUGLAS PKOPOSAL FOR DUAL AIRSPEED LIMITATIONS ON THE MODRL DC-8F; WE-210 MEMORANDUM DATD JANUARY 30, 1962 (Issued 17 July 1963) 1. ORIGIN. The Douglas letter dated September 18, 1961, to the Western Region requiring the establishment of a dual airspeed limitation of the DC-8F. This model is a multipurpose aircraft which will be operated as an all-passenger airplane, an all-cargo airplane, or a combination passenger and cargo airplane. Due to the higher density of cargo loading as compared to passenger loading and a desire to provide as much operational flexibility as possible, Douglas will certify higher zero fuel weights for use when a cargo load or a cbmbination cargo- passenger load would cause the airplane weight to exceed the normal zero fuel weight. At the higher zero fuel weights, the airplane becomes gust critical in the high dynamic pressure region, "Q", and the maximum operating limit speed VNO (VMo) must be reduced. This has created a problem in the marking of the airspeed indicator and the setting of the overspeed warning sensor to provide for the two limiting speed ranges. 2. REGULATIONS AFFECTED. a. CAR 4b.730 Markings and Placards, General b. CAR 4b.732 Airspeed Limitation Information C. CAR .4b.741(a)(2) Operating Limitations 3. HISTORY The Douglas Aircraft Company letter dated September 18, 1961, to the Western Region requested concurrence with its proposal to install a dual airspeed limitation and overwarning sensor on the DC-8F in accordance with the proposed Special Civil Air Regulation published in the Federal Register dated June 8, 1961. The Douglas proposal calls for the addition of a red radial line to the airspeed indicator and a modification of the sensor by one of the following: a. Remove the passenger unit and install a cargo unit. b. Install a dual unit with a selector switch. Chap 3 Par 1 Page 45 6 Jan 71 The Douglas hirkraft Company proposal further calls for the addition of the following to the airplane flight manual limitations section: When operating in an all-passenger configuration, do not exceed the "barber pole". When operating in a partial or all-cargo configuration, do not exceed either the "barber pole" or the red line. The Western Region Engineering and Manufacturing Branch letter dated December 1, 1961, to Douglas stated they do not concur with the proposed dual airspeed system for the following reasons: a. Possible error or confusion on the part of the crew since they would be required to disregard the red line when flying the "barber pole". b. With the present instrument panel and cockpit lighting system on DC-8 airplanes, the red line marking would not be visible under night lighting conditions. Howe&r, a dual overspeed warning sensor would be acceptable. The Douglas AircraFt Company letter to the Western Region dated January 4, 1962, proposed to use an instrument with a two position "settable" red line in conjunction with a dual overspeed sensor with a selector switch. WE-210 memorandum to FS-100 dated January 30, 1962, requested comments on the Douglas proposal and set forth the following with regard to the Douglas proposal dated January 4, 1962: a. It does not appear feasible from an operational. and safety standpoint to make the crew responsible for determining whether the red line or the "barber pole" should be observed. This could lead to confusion and error since the crew must also manually set the dual overspeed warning system dependent upon aircraft configuration. b. The "resettable" red line may not meet the intent of policy established for the Convair Model 990 by FS-100 memorandum to the Western Region dated January 27, 1961. This policy required distinctive and unmistakable placards for dual airspeed limitations. Page 46 Chap 3 Par 3 6 Jan 71 c 4. SUMMARY. 8110.6 a. b. C. d. e. f. h. The current airworthiness requirements, CAR 4b, do not prohibit the establishment of a dual airspeed limitation. The currently applicable airworthiness requirements, CAR 4b.732, states that airspeed limitations shall be presented in such a manner that they can be easily read and interpreted by the flight crew. The currently applicable airworthiness requirement, CAR 4b.741, states that the normal operating speed, VNO, shall be presented to the flight crew in accordance with section 4b.732 (b. above). The currently applicable section CAR 4b.730, states that additional information, placards, and instrument markings having a direct and important bearing on safe operation of the airplane shall be required when unusual operating characteristics warrant. The system proposed by Douglas does not present an easily inter- preted airspeed indication in that the use of the "barber pole" or red line is dependent upon a particular configuration; wherein, the red line is limiting rather than the "barber pole" as is normally the situation. The Douglas proposal does not provide for changing the maximum speed "barber pole" needle cam to provide a continuous indication of v (or V ) at all altitudes. Such indication has been requyqed for"zll turbojet aircraft including the standard DC-8 series. The dual setting of the overspeed warning sensor, as proposed by Douglas, is satisfactory, provided adequate procedures and instructions are developed to preclude improper setting. The procedures should at least include an AF'M limitation and a check item on the cockpit checklist. Instructions must be provided for airline operations personnel which will require the appropriate setting for each zero fuel weight. c When the zero fuel weil;ht exceeds 187,000 pounds, the normal operating limit speed is reduced a maximum of 22 knots in the altitude range of 10,000 to 27,000 feet due to structural considerations. 7. c: Chap 3 Par 4 Page 47 8110.6 6 Jan 71 5. CONCLUSIONS. In consideration of the above, the Douglas proposal for establishing dual airspeed limitations for the Model DC-W is found unacceptable since it does not comply with CAR 4b.730 and 4b.732 for the following reasons: a. There is no provision for maximum speed "barber pole" needle indication of VNO or VMO when the lower airspeed limits are appli- cable. It would be confusing to the pilots to observe the "barber pole" for one condition and not the other. b. The dual red line marking of the airspeed inldicator could be too easily misset or tampered with after setting, thereby giving the pilots erroneous limitations information. c. The red lines are not acceptable because they would lose their significance and be confusing to the pilots. d. Adequate instructions, procedures, and limitations for the setting of the dual overspeed warning sensor are not provided. Page 48 Chap 3 Par 5 6 Jan 71 . 8110.6 l - “Ldl REVIEW CASE'NO. lo. RULING ON APPLICABILITY OF AIRFLOW PROVISIONS IN CIVIL AIR REGULATIONS 7.382(a), CARGO AND BAGGAGE COMPARTMENTS, TO VERTOL MCDEL 107-II ALL CARGO HELICOPTER (Issued 17 July 1963) 1. INTRODIJCTION. Vertol Division of The Boeing Company has proposed to the Eastern Region, EA-212, for the Vertol Model 107-II all cargo helicopter, that the pro- visions of Cargo Compartment Classification, Class E, CAR 4b.383(e)(3), "Means shall be provided to shut off the ventilating airflow to or within the compartment. Controls for such means shall be accessible to the flight crew in the crew compartment," and CAR 4b,383(e)(5), "Required crew emergency exits shall remain accessible under all cargo loading conditions," be used in lieu of the airflow provisions specified in CAR 7.382(a), "Design of inaccessible compartments and sealing of these compartments shall be such as to contain cargo compartment fires for a period of time sufficient to permit landing and safe evacuation of the occupants," on the premise that the airflow provisions of CAR 7.382(a) are inapplicable to an all cargo version helicopter. The Eastern Region concurs with the request and has asked for Washington Office concurrence and/or comments. 20 CHRONOLOGICAL HISTORY. a. Eastern Region, EA-212, teletype message of February 16, 1962, to Washington Office, FS-120, outlining problem and requesting concur- rence and/or comment with Eastern Region recommendations. b. Washington Office, FS-120, teletype message of February.27, 1962, indicating answer forthcoming in an Engineering and Manufacturing Division Review Case. 3. EACTS IN TPE CASE. a. CAR 7.382 does not contain provisions similar to those in CAR 4b.383(e)(3) and (5) directly applicable to an all'cargb helicopter. 1 b. At the time of inception of CAR 7, Rotorcraft Airworthiness, Transport Categories, the use of all cargo type helicopters was not envisioned. The related requirements were administered pri- marlly in the type certification of passenger-carrying helicopters. C. The shortcoming in CAR :+b was recognized with issuance of Amendment 4b-10, issued April 17, 1959, which established a new Class E cargo compartment applicable to fixed-wing transport aircrafr- used for the carriage of cargo only. The basis for issuance of Amendment 4b-10 is contained in the preface thereto and is considered equally valid for a transport helicopter. Chap 3 Par 1 Page 49 6 Jan 71 d. In the absence of a requirement in CAR 7 directly applicable to the Vertol request, the provisions of CAR 7.10, Eligibility for Type Certificate, may be invoked by the Administrator. 4. CONCLUSIONS. - *. ., In consideration of the foregoing, it is concluded under the provisions of CAK 7,lO that the Vertol Model 107-11 all cargo helicopter shall be eligible for typ'? certification providing: a . Compliance is shown with the provisions of CAR 4b.383(e)(3) in lieu of the airflow provisions contained in CAB 7.382(a). b. Compliance is shown with the provisions of CAR 4b.383(e)(5) relative to accessibility of crew emergency exits. c. Compliance is shown with the provisions of CAR 4b.380(c), Protective Breathing Equipment, "If the airplane contains Class A, B, or E cargo compartments, protective breathing equipment shall be installed for the use of appropriate crew members," in lieu of CAR 7.382(c), "If compartments are intended to be accessible in flight, protective breathing equipment shall be available for the use of the appropriate crew member." d. Compliance is shown with the provisions of CAB 4b.382(d), "Sources of heat within the compartment shall be shielded and insulated to prevent igniting the cargo." e. Compliance is shown with the provisions of CAB 7.382 except those relative to airflow in CAR 7.382(a) and protective breathing equipment in CAR 7.382(c). Cnap 3 Par 4 Page 50 6 Jan 71 8110. 6 ‘L+f REZVIEW CASE NO. 11. CESSNA AIRCRAFT COMPANY RtiQUEST FOR APPROVAL OF THE EMERGENCY JZIT PROVISIONS ON THEIR SIX-PLACE VERSIONS OF NRCRAPT MODEXS 310E THROUGH 31CH. 320, m 320~ (17 July 1963) 1. INTRODUCTION. The Cessna Aircraft Company has requested the Central Region to approve an increase in the maximum occupancy of their Models 310E through 31OH, 320, and 320A from 5 to 6 persons. Cessna contends under CAR 3.10, Eligibility for Type Certificate, that the undersize emergency exit pro- vided on the left side is just as effective as the exit type prescribed in CAR 3,387, Exits. Cessna also proposes the addition of a second emergency exit means on the right side. The Central Region reconunends approval of the 6 place versions proposed by Cessna but has requested concurrence from the Washington Office before advising the applicant, particularly as the equivalent level of safety provisions of CAR 3.10 are involved. 2. CHRONOLOGICAL HISTORY. a. In a letter dated February 10, 1962, to the Central Region, Mr. W. H. Prewitt, Chief Administrative Engineer, Cessna Aircraft Company, acting in the capacity of DMCR' 3-3, requested concurrence of his action as follows: ! "beginning with the 1963 Models 320A and 310H, Cessna intends to offer six-place versions of these aircraft. "CAR 3.387 requires that an emergency exit opening be provided, the minimum dimensions of which shall be such that a 19 by 26 inch ellipse may be completely inscribed therein. "Although these openings do not meet the exact requirement specified, they are of adequate shape and area to serve the purpose intended. A copy of Report 1547 is enclosed. This report, originally prepared for purposes of ex- porting Model 310 aircraft to Canada, documents that compliance with the intent of the regulations has been demonstrated. "Therefore, I am approving the emergency exit openings for the above models when used as six-place aircraft in that an equivalent levei of safety has been provided and demonstrated. It is requested that your office in- dicate by return letter your concurrence with this approval." Chap 3 Par 1 Page 51 8110.6 6 Jan 71 b. The Central Reg-ion reply dated February 24, 1962, stated: "Our evaluation of tl-:e data indicates that the exits are inadequate for approlral inasmuch as the height of the exits would be shy by 3.5 ilnd 5.5 inches from that necessary to permit a 19 by 26 inch ellipse to be inscribed therein. The photographs, although indicating a man might escape through the exit, are not considered justification for deviating from CAR 3.387. In the past, demonstrations have been used to verify numbers of persons utilizing the exits, but not to justify reductions of sizes of the amount indicated in this case." c. The matter was presented to the Washington Office for resolution by Mr. W. H. Prewitt, DMCR 3-3, in a letter dated March 5, 1962, to the Director, Flight Standards Service. His letter stated in part: "It is Cessna's contention that the present emergency exit provided an equivalent level of safety and that it has been so demonstrated by tests and service experience. Further, an undue hardship would be placed upon the manufafturer in order to meet the exact dimensional requirements Specified by CAR 3.387. "In summary, I believe the emergency exit provisiocs should be considered to meet the intent of the regulations for the following reasons: (a) No significant increase in safety will result by enlarging the opening. (b) At the time the basic airframe structure was certifi- cated, actual demonstrations were being accepted in lieu of meeting exact dimensional requirements. cc> The utilization of the Models 310 and 320 as a six-place aircraft is a normal development that should not require extensive change nor place an undue hardship upon the manufacturer. (d) A generous sized baggage door can also be used as an emergency exit by the passenger in the sixth seat." d. In a meeting held on March 13, 1962, between Mr. W. H. Prewitt, DMCR 3-3, and representatives of the Airframe Branch, FS-120, and Mr. W. Anderson, Central Region, Mr. Prewitt was advised that approval could not be granted unless, under CAR 3.10, it was shown that the emergency exit means provided is just as effective Page 52 Chap 3 Par 2 6 Jan 71 8110. 6 as the one prescribedin CAR 3.387. Conduct of evacuation tests and use of the baggage door as an emergency exit were suggested. e. In a letter dated March 19, 1962, to the Central Region, Mr. W. H. Prewitt stated: "As previously pointed out in Cessna letters 178-2-30 and 178-3-9, the company intends to offer six-place versions of the Models 310E through H, 320, and 320A. The standard emergency exit required for six-place aircraft is an opening such that a 19 by 26 inch ellipse may be completely inscribed therein. The pre- sent Model 310's and 320's have an emergency exit which is smaller than that noted above. However, they have a baggage door which the passengers can use for emergency exit. Both of these exits are of adequate size and shape to permit rapid evacuation of the air- craft in case of emergency. In fact, the time required is greatly reduced below that which would be required if only one standard size opening were provided. "Enclosed is Report 31OG-6212-021, which shows the ?! emergency exits that have been provided for the S@odels 310E through 310H, 320 and 320A. It verifies that the level of safety is greater than that required by; CAR 3.387." f. In a memorandum dated March 20, 1962, to the Washington Office, the Central Region recommended approval of the Models 310E through H, 320 and 320A aircraft for six passengers on an equivalent safety basis in lieu of literal compliance with the emergency exit size requirement of CAR 3.387. Recommended approval was contingent on demonstrations conducted using the baggage door as an emergency exit to verify that egress through the window exit; also demonstrations that egress through the window exit on the Cessna 310E through 310H was no more difficult than through the 19 by 26 inch elliptical opening even though the window height was considerably less than 19 inches. g* Washington requested Central Region on March 29, 1962, to provide comparative evacuation test times, using six persons; Three evacuation tests were asked for - baggage door, current exit, and a 19 by 26 ellipse. h. The Central Region's priority wire dated March 30, 1962, to Washington stated: 0 kd Chap 3 Par 2 Page 53 8110. 6 6 Jan 71 "Re phone this date. Cessna evacuation test con- ducted four men and two women. Total evacuation time 310G exit 33 seconds, 19 x 26 ellipse 29.6 seconds, baggage door 20.1 seconds. Tests appli- cable to 310E and up. Reference copy Cessna February 16, 1962, letter. Cessna not asking approval for Models 310 through 310D. Detailed report to follow." 3. FACTS IN THE CASE. a. The Cessna Aircraft Company Models 310 and 320 series were developed as five-place aircraft and type certificated under CAR 3, dated November 1949, including Amendments 3-1, through 3-10. The main cabin entrance on these aircraft is on the right side with the emergency exit on the left side. Under the provisions of CAR 3.387, Exits, an emergency exit is not required on aircraft approved to carry five persons or less. b. Cessna Aircraft Company now intends to offer optional six-place versions of Models 310E through 31OH, 320, and 320A. The baggage area is replaced by the sixth seat and the baggage door is used as an additional emergency exit. C. Cessna has conducted evacuation tests to establish under the provisions of CAR 3.10 that the emergency exit means is just as effective as prescribed in CAR 3.387. The exit configura- tions tested are shown below: hl h2 w Area, Square Inches Model 310E, F, G, H 15 12 26 373 Model 320, 320A 16 15 26 429 Ellipse (19 x 26) 388 Baggage Door 22% 25 21% 494 Six occupants were all seated with safety belts fastened. Sex M M M M Fm Fm Height 5' 8" 6' 1" 5' 9$" 5' 9%" 5' 3%" 5' 7" hEi 231 lbs. 38 210 lbs. 39 185 lbs. 33 150 lbs. 28 115 lbs. 40 118 lbs. 45 Chap 3 Par 3 Page 54 6 Jan 71 do, 8 The following tests were conducted: Test No. 1 - Time to unfasten seat belt and kick out exit door - 6 seconds Test No. 2 - Evacuation through Cessna 310G exit - 33 seconds Test No. 3 - Time to evacuate thru 19 x 26 ellipse - 29.6 seconds Test No. 4 - Time to evacuate thru baggage door - 20.1 seconds Test No. 5 - Rerun of Test No. 2 - 23.1 seconds Test No. 6 - Rerun of Test No. 3 - 21.1 seconds Analysis of the foregoing indicates the area of the exit on the Cessna 310E through H is 96 percent of the area of a 19 x 26 ellipse, or only 4 percent less than required. For the Models 320 and 320A there is more actual area than a 19 x 26 inch ellipse provides, thus indicating the evacuation time through the Models 320 and 320A would probably be less than for the ellipse. The baggage door also has considerably more actual exit area on both the Cessna 310 and 320 series than a 19 x 26 inch ellipse provides. Analysis of the evacuation times indicates very little significant time differences between the Cessna 310E through H series and a 19 x 26 inch ellipse. Likewise, the total time is considerably less than might have been expected in a test of this kind. These factors alone would support acceptance of the left hand exit as being equivalent to that prescribed in CAR 3.387. In addition, there is the extra safety feature present of an additional exit on the right side. Admittedly it does not support the claim of equivalent safety for the left side of the aircraft under all emergency situations, but it is considered a highly desirable safety provision. The evacuation time through it was only 20 seconds, hence, in situations where both the left and right side exits are useable, the total aircraft evacuation time would be greatly reduced. It should also be noted that under the present requirements of CAR 3.387 for a five-place aircraft no emergency exit is needed. For a passenger capacity of 6 - 15 one emergency exit is needed. .Page 55 8110. 6 6 Jan 71 In the case at hand the applicant has only added one person, i.e., he has gone from a five to a Six-place version aircraft. Under the literal provisions he must have an emergency exit. He has, but it is not in literal conformance with the dimensions prescribed. The evacuation tests show the effectiveness of the exit he provided is almost comparable to an elliptical exit. Furthermore, the applicant has shown he is providing an additional exit on the opposite side that is superior to the elliptical shaped exit as an evacuation means. This exit is being added in part to account for the transition from a five to a six-place version and must certainly be considered as an additional highly desirable safety provision in the overall appraisal of the problem. CONCLUSIONS. In consideration of the foregoing it is concluded under the provisions of CAR 3.10 that the Cessna Aircraft Company has satisfactorily shown that the emergency exit means provided on their Models 310E through 310H, 320, and