Supplemental Type Certificate for Beechcraft Model 18

peller slash marks, damage, the position of the domes, and pitch settings at impact indicated that both propellers were in the 20-23-degree position (flight range) at time of impact. According to the applicable Federal Regulations, the pilot-in-command was responsible for proper loading of the aircraft. There was conflicting testi- mony as to whether the pilot computed the weight and balance on N2999 before departure from Gainesville. Company records revealed that ten pieces of luggage, weighing a total of 209 pounds, were placed aboard N2999. Three of these bags were placed in the nose baggage compartment. Remnants of seven suitcases as well as pieces of smaller luggage were recovered from the rear baggage area. However, due to fire, no positive weight determination could be made. The pilot and all the passengers were identified and located as to their positions in the aircraft at time of impact. The weight of each passenger and an estimate of the baggage weight for each were obtained from the next-of-kın. The combined weight of the nine passengers was estimated to be 1,484 pounds. The takeoff weight was computed to be 9,402 pounds with a c.g.4 of 124.7 inches The takeoff weight was computed to be 9,402 pounds with a c.8.4 of 124.7.11 125.9 inches. The aft c.g. limit of this aircraft was 117.7 inches. N2999 was originally manufactured by the Beech Aircraft Corporation as a Beech D18S certificated in accordance with FAA Aircraft Specifications. 6/ On September 29, 1962, Supplemental Type Certificate 7/ (STC) No. SA2-1246 was 4 C.g. is the point on an airplance about which the weight is evenly distributed or balanced, measured in inches from a designated datum line. Loading of the aircraft must be such that the c.g. will be confined within the c.g. limits or the aircraft will not be capable of flight because of a lack of flight equilibrium. 5 See Attachment II. 6/ FAA Spec. No. A-765 authorized a maximum gross weight for takeoff of 8,750 pounds and a c.g. range of 109.8 to 117.7 inchdes. 7 A certificate required by the FAA of anyone who alters an aeronautical product by introducing a major change in a previously approved type design and * which is not so extensive as to require application for a new type certificate. * The basic rules, policies, and procedures governing certificates are stated in Paragraphs 1.25 thru 1.28-1 of Civil Aeronautics Manual 1. - 4 2 , In issued to Airline Training Incorporated (ATI), also known as Conrad Inter- national Corporation, Inc., which authorized the conversion of certain models of the Beech aircraft, approved an increase in the maximum gross takeoff weight to 10,200 pounds, and extended the aft c.g. limits to 120.5 inches. December of 1963, ATI applied for FAA approval of an "economy version" of the Beech 18 which would allow a maximum gross takeoff weight of 9,360 pounds and extend the rear c.g. limit from 117.7 inches to 120.5 inches. 8/ The Federal Aviation Agency's Engineering and Manufacturing District Office (EMDO), at Miami, decided to treat this latter STC as an amendment to the original (SA 2-1246) rather than as a new STC. The Flight Manual Supplement for the "9,360" conversion was approved by the EMDO on January 10, 1964, to allow time for printing. Meanwhile, the EMDO was conducting conformity inspection of the ATI engineering drawings and flight tests at the ATI facility at Fort Lauder- dale, Florida. With the approved Flight Manual Supplement, and an STC number only, but without approval of the amended STC, the president of ATI contracted for modi- fication of at least two aircraft of which one was N2999. These aircraft were modified in accordance with the unapproved application for an amended SRC. How-. ever, this modification was never approved by the FAA due to the absence of an elevator-down spring. Since the modification included the extension of the aft c.g. limits of the Beech D18S the down-spring was required in order that the control inputs during all regimes of flight would be in accordance with the certification requirements under Part 3, Civil Air Regulations. The installation or deletion of this spring does not affect elevator power or authority of the pilot but merely keeps the stick forces required by the pilot within a normal envelope of acceptable limits. The N2999 had eight passenger seats and two pilots' seats installed. empty weight and c.g. as shown on the latest FAA Form 3379/ and the require- ments of Part 3 10 of the Civil Air Regulations indicate that it was not pos- sible to put a 170-pound passenger in each seat without exceeding the aft c.g; limit. Addition of any fuel to the aircraft then moved the c.g. further aft. It was not possible to operate N2999 with eight passengers unless ballast was carried in the nose compartment. There were no placards to warn of these dangerous loading restrictions, nor were any required by the provisions of Part 3 of the Civil Air Regulations. The Form 337, submitted upon installation of the eight seats, was accepted by the FAA General Aviation District Office (GADO) in Miami, without any review to determine if the aircraft complied with the weight and balance provisions of 8/ The 9,360 conversion of the D-18 Beech includes high performance wing tips (SA 2-213); changing of the angle of incidence of the horizontal stabilizer and installing elevator gap seals (SA 2-383); stall strips, engine cooling ramps, carburetor ram air scoop and heat modifications (SA 2-1246); retracting tail wheel (SA 2-1230); tail bubble doors (SE 2-1261); and Airstair rear door (SA 2-566). 2/ An application for approval by FAA, which must be executed in duplicate of each major repair and/or alteration made to an aircraft, airframe, powerplant propeller, or applicance. 10/ See Attachment III. ነ - 5 - Part 3 of the Civil Air Regulations. Although computations were checked for accuracy, there was no check to determine the validity of the figures used as the basis for the computations. There was no review to see if the aircraft could operate with the eight seats occupied and still comply with the pro- visions of Part 3 of the Civil Air Regulations. Following review by the GADO, the Form 337 was forwarded to the FAA Central File in Oklahoma City, Oklahoma. According to the investigation and testimony at the hearing, this is the standard FAA practice in respect to processing of 337 Forms. An aft baggage compartment was installed on the right side opposite the most rearward seat. This required the removal of the rear bulkhead at fuselage station 9. This compartment was limited to 276 pounds of baggage when the rear seat was not occupied. It was further limited to 106 pounds when the seat was occupied. The new empty c.g. of the 9,360 conversion was 114.53 inches. ards were required in both the nose and the aft baggage compartments indicating their maximum load capacity. There was conflicting testimony as to whether these placards were installed. Plac- South Central Airlines, Inc., received N2999 in late January as modified in accordance with the proposed 9,360 conversion and scheduled revenue flights were begun with the aircraft on January 29, 1964. An application for registra- tion of N2999, dated January 30, 1964, was submitted to the FAA. The aircraft was flown in scheduled revenue service on January 30, 31, and February 1, and 2, 1964. Some of these flights were under maximum load conditions at or near the unapproved gross weight condition of 9,360 pounds. A Federal Aviation Form 2417 11/ for the 9,360 conversion of N2999, ındı- cates an approval date of January 10, 1964, for the amendment to STC SA 2-1246. However, the investigation revealed that the form was not approved and signed by the supervisor of the EMDO until February 24, 1964, and was delivered to ATI the following day. FAA personnel explained that back dating of STCs is a standard practice. An airplane flight manual was required by Sec. 3.777 of the Civil Air Regulations to be aboard each aircraft over 6,000 pounds. Such manuals contain information which has an important bearing on safe operation, including weight and balance data. According to company personnel, there was an airplane flight manual aboard N2999 at the time of the accident. However, no evidence of this manual was found in the wreckage. In any event, an identical copy of a Flight Manual alleged to have been in the aircraft did not contain information or charts about the seat locations or baggage compartments of this aircraft. No evidence of a cockpit checklist was found in the wreckage. There was conflicting testimony as to whether a cockpit checklist was present in the air- craft prior to the accident. Company officials presented two checklists they stated were being used in their Twin Beech aircraft. Neither was applicable to this airplane. 11 FAA Form 2417 is an application for a Supplemental Type Certificate which is submitted in triplicate to the local FAA Flight Standards Inspector. - 6 - It was determined that the pilot of N2999 had been discharged from the U. S. Navy in 1954 on a 100 percent physical disability due to arthritis and deafness. The pilot's logbook indicated he had a total of 16,647 flying hours when hired by South Central in May 1963. He had accumulated approximately 150 flying hours in Twin Beech type aircraft since that time. Analysis Atmospheric conditions and airport facilities were not factors in this accident. Metallurgical examination of the impeller teeth of the right engine indi- cated that the failures were of the overload type and had occurred at impact due to the sudden stoppage of the engine. Both engines were capable of normal operation up to the time of impact. Structural investigation showed no evidence of any failure or malfunction of the airframe prior to impact. The pilot possessed the proper certificates required by the FAA for the operation involved. His commercial pilot's license and second-class medical certificate were current and he had flown 150 hours in D18S aircraft within recent months. His actual proficiency level in the aircraft could not be de- termined since no flight crew training or proficiency records were kept. There was no indication that the pilot's physical disability contributed to this accident. However, it is significant that the FAA medical certification pro- gram did not focus attention on the fact that a medical disability was ındı- cated on one of the pilot's medical certificate application forms. Some of the weights used in the Board's weight and balance computations are estimates. However, considering the sources of these estimates, the gross weight and c.g. derived from the computations are conservative and valid. These computations reveal that the aircraft was overloaded and excessively tail heavy. The aircraft exceeded the maximum allowable gross weight of the basic D18S specifications by 652 pounds and the rearward c.g. limit by 8.2 inches, gear retracted. The aircraft exceeded the proposed maximum gross weight of the 9,360 conversion by 42 pounds and the rearward c.g. limit by 5.4 inches, gear retracted. When the c.g. of an airplane lies sufficiently forward of the neutral point, 12/ the airplane possesses a positive static longitudinal stability. 13/ As the c.g. is moved rearward beyond the rear limits, and beyond the neutral point, the aircraft will become unstable. If the c.g. is moved sufficiently rearward of the neutral stability point there may not be sufficient elevator effectiveness to reverse an unwanted pitching motion. 12 That c.g. position at which the slope of the curve of pitching- moment coefficient versus angle of attach is equal to zero. 13/ Positive static longitudinal stability occurs at any c.g. position at which the slope of the curve of pitching-moment coefficient versus angle of attack is negative. Negative static longitudinal stability occurs at c.g. position at which the slope of the curve of pitching-moment coefficient versus angle of attack is positive. 7 -7- N2999 had been modified in accordance with a proposed STC to increase the maximum takeoff gross weight, extend the aft c.g. limit, and, in accordance with an FAA Form 337, modify the passenger compartment by installing eight seats and a baggage compartment. This STC had not been approved prior to the approval of the Flight Manual Supplement, nor at the time of the accident. The approval did not occur until February 24, 1964. The practice of back- dating the STC opened the door to operation of an unairworthy aircraft. The landing gear was up and flaps were in the full-down position at time of impact. The full-flap condition in this aircraft does two things. It moves the center of lift aft, causes a slower than normal lift-off speed and produces drag. However, the c.g. was so far aft of the aircraft's controllability limits that the effect of full flaps was negligible. The full nosedown elevator trim position verifies the tail heavy loading of the aircraft at the time of the accident and indicates an attempt by the pilot to lower the nose by use of trim in addition to the use of the elevator. The Board concludes that N2999 was loaded to a c.g. of plus 125.9 inches aft of datum with the landing gear retracted. The allowable rear c.g. limit of the proposed STC modification was only 120.5 inches, but in this aircraft, it was actually 117.7 inches due to the lack of the elevator-down spring. Takeoff appeared to be normal until gear retraction when uncontrolled maneuvers were observed which were typical of an aircraft which is unstable due to an excessive aft c.g. The out-of-c.g. condition, aggravated further by the rearward shift in center of gravity due to gear retraction, placed the aircraft outside its aero- dynamic control parameter with insufficient elevator effectiveness to prevent an excessively nose-high attitude%3B this resulted in a low altitude stall shortly after takeoff from which recovery was not possible. Probable Cause The Board determines the probable cause of this accident was the pilot's failure to properly load the aircraft, resulting in insufficient elevator effectiveness to reverse an unwanted pitching motion. Recommendations As a result of this accident, the Board sent two letters of recommendation to the Administrator, Federal Aviation Agency. They were dated February 28, 1964, and May 8, 1964, and appear as attachments to this report. (See Attach- ments IV and V.) BY THE CIVIL AERONAUTICS BOARD: /s/ ALAN S. BOYD Chairman /s/ ROBERT T. MURPHY Vice Chairman /s/ CHAN GURNEY Member /s/ G. JOSEPH MINETTI Member /s/ WHITNEY GILLILLAND Member 1 | SUPPLEMENTAL DATA Investigation The Civil Aeronautics Board was notified of this accident shortly after its occurrence on February 3, 1964. An investigation was immediately initiated in accordance with the provisions of Title VII of the Federal Aviation Act of 1958, as amended. A public hearing was held at Gainesville, Florida, on March 24-26, 1964. Air Taxi Operator South Central Airlines, Inc., holds Air Taxi Operator Certificate No. 8-SO-36 issued by the Federal Aviation Agency. It operates scheduled flights to approximately 26 airports within the State of Florida. Flight Personnel Homer Roger Lee Thompson, age 47, was first employed by South Central Airlines, Inc., on May 4, 1963, and had accumulated a total of 16,647 hours flight time of which 486 hours were in Twin-Beech type aircraft. He held currently effective FAA commercial pilot certificate No. 26930-40, airplane single and multiengine land with instrument and flight instructor rating. Records indicated he had been discharged from the U. S. Navy with a disability rating of 100 percent in November 1954. In October 1959, he was placed on the permanent disability retired list with a disability rating of 100 percent. His condition at that time was classified as arthritis due to trauma rated as severe limitation of motion of the lumbar spine, rheumatoid arthritis and slight impairment of auditory acuity. He held an FAA second-class medical certificate issued July 2, 1963, with the following limitations: possess correcting glasses for near vision while exercising the privileges of his airman certificate." "Holder shall He satisfactorily passed a company flight check May 12, 1963, using a Piper Aztec (PA-23-250), and an FAA instrument check on May 17, 1963, using a Piper Aztec (PA-23-250). Aircraft N2999 was originally sold by the manufacturer, Beech Aircraft Corporation, Wichita, Kansas, as a Beech D18S, N1823D, serial No. A-811. In 1953, the air- craft was reregistered by the then owner as N2999. At the time of the accident, it was equipped with two Pratt & Whitney model R 985-AN14B engines with Hamilton Standard model 22D30 prepellers. The left engine, serial No. JP206311 was over- hauled on January 8, 1964, with total time of 2,514:30 hours. The right engine serial No. JP227420 was overhauled on January 9, 1964, with total time of approx- imately 1,500 hours. The preflight inspection form of February 2, 1964, indicated N2999 had flown 33:19 hours since the last 100-hour inspection. 1 1 1 1 MAS NORTH -1° 45 059° TERMINAL FAR FLIGHT SERVICE STATION 5027 150 ASPHALT ELEVATION 155 FEET WATER TANK HANGAR MAIN WRECKAGE ☑ 1 : 059° RIGHT PROPELLER RED 330 GLASS ° 270° Initial Impact- NOTE AIRCRAFT NOT TO SCALE GAINESVILLE MUNICIPAL AIRPORT RUNWAY 1000' 2000' SCALE 65 52 300° 220° MAIN WRECKAGE LEFT WING & ENGINE CYLINDER DEPRESSION a SMALL PARTS OF ENGINE T 20 PROPELLER MARKS .79 ° 10 20 100 SCALE-FEET CIVIL AERONAUTICS BOARD LAYOUT and WRECKAGE DISTRIBUTION CHART SOUTH CENTRAL AIRLINES BEECHCRAFT DIBS N2999 GAINESVILLE, FLORIDA - FEBRUARY 3, 1964 * J ' ATTACHMENT II Aircraft empty weight Oil, 13-1/2 gals. @ 7.4 lbs. per gal. Weight Arm Moment 6,379.1 114.53 730,031.4 99.9 93.0 9,290.7 Fuel, 127 gals. front tanks @ 5.86 lbs. per gal. (Note: Full tanks minus 25 gals. burn-off on flight Ocala to Gainesville) 744.2 126.0 93,769.2 Fuel, rear tanks, 50 gals. @ 5.86 lbs. per gal. 293.0 155.0 45,415.0 Pilot 172.0 87.0 14,964.0 Passenger in copilot seat 135.0 87.0 11,745.0 Passenger No. 2 110.0 125.0 13,750.0 L Passenger No. 3 169.0 124.0 20,956.0 Passenger No. 4 172.0 156.5 26,918.0 Passenger No. 5 180.0 153.0 27,540.0 Passenger No. 6 178.0 188.0 33,464.0 Passenger No. 7 150.0 182.5 27,375.0 Passenger No. 8 185.0 243.0 44,955.0 Passenger No. 9 205.0 212.0 43,460.0 Baggage, nose compartment 130.0 36.0 4,680.0 Baggage, aft compartment 100.0 243.0 24,300.0 Total takeoff weight & c.g. 9,402.2 124.7 1,172,603.3 Landing gear "UP" condition 9,402.2 125.9 1,184,603.3 ATTACHMENT III 3.74 MAXIMUM WEIGHT. (a) The maximum weight shall not exceed any of the following: (1) The weight selected by the applicant. (2) The design weight for which the structure has been proven, except as provided in § 3.242 for multiengine airplanes. (Revised 3-13, August 25, 1955) (3) The maximum weight at which compliance with all of the applicable flight requirements has been demonstrated. (Revised 3-13, August 25, 1955) (b) The maximum weight shall not be less than the weights under the loading conditions prescribed in subparagraphs (1) and (2) of this para- graph assuming that the weight of the occupants in each of the seats is 170 pounds for the normal category and 190 pounds for the utility and acrobatic categories, unless placarded otherwise. (Revised 3-13, August 25, 1955) (1) All seats occupied, oil to full tank capacity, and at least a fuel supply for one-half hour operation at rated maximum continuous power. (Revised 3-13, August 25, 1955) (2) Fuel and oil to full tank capacities, and minimum crew. (Revised 3-17, August 12, 1957) 3.75 MINIMUM WEIGHT. The minimum weight shall not exceed the sum of the weights of the following: (a) The empty weight as defined by # 3.73. (b) The minimum crew necessary to operate the airplane (170 pounds for each crew member). (c) Fuel and Oil quantities not greater than the minima specified in § 3.74 (b)(1). (Revised 3-2, August 12, 1957) 3.76 CENTER OF GRAVITY POSITION. If the center of gravity position under any possible loading condition between the maximum weight as specified in § 3.74 and thè minimum weight as specified in 3.75 lies beyond (a) the extremes selected by the applicant, or (b) the extremes for which the structure has been proven, or (c) the extremes for which compliance with all functional requirements were demon- strated, loading instructions shall be provided in the Airplane Flight Manual as specified in § § 3.777 · 3.780. - 0024 ATTACHMENT IV CIVIL AERONAUTICS BOARD Washington, D. C. February 28, 1964 Mr. George S. Moore Director, Flight Standards Service Federal Aviation Agency Washington, D. C., 20553 Dear Mr. Moore: During the course of our investigation of the accident involving a South Central Airlines Twin Beechcraft at Gainesville, Florida, on February 3, 1964, the Civil Air Regulations governing such operations were necessarily given very close scrutiny. This review brought to light the fact that Part 42a, under which this operation was being conducted, contains no provisions with respect to the following: 1. 2. 3. Flight time limitations. Requirements for initial and recurrent training and proficiency checks as well as company records regarding same. Definition of "flight deck" and conditions under which a passenger may be carried in the pilot's compartment. 4. Development, maintenance and approval of a company operations manual. South Central Airlines is one of several air taxi operators operating under Part 42a of the Civil Air Regulations and employing large numbers of twin engine aircraft in extensive scheduled operations. In view of the scheduled nature of such operations and the relatively large numbers of passengers carried, it is our opinion that appro- priate regulations covering matters such as those cited above should be promulgated at an early date in the interest of assuring an adequate level of safety. , Mr. George S. Moore (2) It is recommended, therefore, that urgent consideration be given to the drafting of a new sub-part of the Federal Aviation Regulations governing air taxi operations such as those conducted by South Central Airlines. The operations to be affected would be those in which a certificate of public convenience and necessity was not involved. Sincerely yours, /s/ B. R. Allen for Leon H. Tanguay Director, Bureau of Safety COPY Mr. Leon H. Tanguay FEDERAL AVIATION AGENCY Washington, D. C. 20553 March 18, 1964 In Reply Refer To: FS-40 Director, Bureau of Safety Civil Aeronautics Board Washington, D. C. 20428 Dear Mr. Tanguay: This is in response to your letter of February 28, 1964, reference: B-80-93, in which you made various recommendations for additional regulation of air taxı operators using twin-engine aircraft in extensive scheduled operations. Your recommendations are most timely and appropriate. As you know, the Agency has just adopted a separate part of the Federal Aviation Regulations (Part 135, enclosed) which will provide a new and effective regulatory base for the certification and operation of air taxis. This Part, while adequate for the vast majority of air taxi operations, may, however, need some more specific attention directed at the kind of problems you have highlighted. To this end, we have already initiated a regulatory project, including necessary field studies. In addition to your recommen- dations, we are giving attention to such other matters as route and ramp checks, aircraft and equipment overhaul requirements, Any specific information you may have substantiating the need for additional regulation of these and other aspects of the scheduled air taxı operations will be most helpful. Sincerely yours, Enclosure George S. Moore Director Flight Standards Service P Y 1024 ATTACHMENT V CIVIL AERONAUTICS BOARD Washington, D. C. May 8, 1964 In reply refer to: B-80-96 Mr. George S. Moore Director Flight Standards Service Federal Aviation Agency Washington, D. C. 20553 Dear Mr. Moore: During our investigation and public hearing in connection with the accident of South Central Airlines' Beech D18-S, N2999, at Gainesville, Florida, February 3, 1964, several points were brought out concerning the issuance of Supplemental Type Certificates and the surveillance of their use. The testimony and exhibits in this case show that STC SA2-1246 was issued to Airline Training Incorporated (also known as Conrad International Corporation) on September 20, 1962. This covered a conversion of certain models of the Beech 18 to raise the maximum gross weight to 10,200 pounds. In December 1963 ATI applied for approval of an 'economy version" which would raise the gross weight to 9360 pounds. It was decided at the Miami EMDO to treat this as an amendment to SA2-1246 for administrative reasons instead of issu- 10 ing a new STC. The Flight Manual Supplement for the 9360 conversion was approved by the EMDO on January 10, 1964, and ATI accepted this as approval of the modification. ATI contracted for modification of at least two aircraft, of which one was N2999, according to the amended STC as applied for, but not as it was later approved. (These aircraft were not equipped with the elevator downspring as required by the approved drawings.) The only approval at this point concerning the amended STC was of the Flight Manual Supplement. Armed with the Flight Manual Supplement approval and an STC number, Mr. W. H. Conrad, president of ATI, in connection with con- tracting for the modification, made the following entry on a Form 337 (Exhibit 4-G, Docket SA 377): Design data for Airline Training Inc. Supplemental Type Certı- ficates is the property of Airline Training Inc. and may only be used with their permission. Permission is hereby granted for use of installation drawings, for Beechcraft D18S, Ser. No. A-811, N2999 only, per Supplemental Type Certificate as follows: 1