CESSNA 172 Aircraft Rev-022 SK4172-42A.DOC

means that the stud is too short for the application or the insert is incorrectly adjusted. No returns accepted on over torqued studs (Studs with loose or missing pins). This is plainly indicated by galled heads on the stud as a result of attempting to force the stud to lock. Cessna issued Service Bulletin SB98-53-02 for newer 172 R & S airplanes on December 31, 1998 to address the root of the problem with shock-mounted cowlings. (Applies to all shock-mounted cowlings). This 29 page service bulletin describes an exhaustive procedure to align cowl mounts and assumes approximately 18 hours to accomplish. Skybolt has developed an alternate procedure that is simple and consumes very little time to properly align mounts with the corresponding fastener hole in the cowling. Step 1 in this manual will describe how to check for mount alignment. The fix to alignment problems is explained throughout the instructions. *****For Firewall Only Conversion Kits****** MARK REAR SIDE HOLES OF UPPER COWLING TO PRECLUDE INADVERTENTLY DRILLING THESE HOLES FOR THE SK-O GROMMET. MARK OR TAPE OVER THIS HOLE. INSTALLATION Converting Southco Fasteners to CLoc® SK40S5 Series Fasteners SKYBOLT SK2003-42 Mounts and SK245-461A Receptacle PLEASE NOTE: The most important points you must adhere to in converting your aircraft are: (1) Reading these instructions will save installation time and costly mistakes. (2) Never drill any holes referenced with a standard drill bit. You must use a step drill or risk damage to the airframe or cowling. (3) The biggest problem we encounter is a lack of understanding on how a CLoc® stud works. These are not Dzus studs where the bigger the screwdriver the better. CLoc® studs require very little torque to lock. Over torquing simply ruins the stud by loosening the pin. Readjust inserts to allow stud to lock with minimum effort. Skybolt Copyright 2016 Page 4 of 13 November 1, 2016 There are three segments of the cowling we refer to in these instructions: (A) The firewall support brackets (B) The lower cowling containing the firewall studs and the side receptacle mounts. (C) The upper cowling containing both firewall and side studs. ADVANTAGES TO CLoc® SK40S5 Series studs: (1) The strongest, most durable panel fastener. SKYBOLT SK203 Series Kits are designed to convert the entire cowling to CLoc® SK40S5 Series fasteners. Tools Required: 3/8 Drill Motor (Extra Drill Motors preferred) Small Open End wrench (11/32) UNIBIT-1 and UNIBIT-3 or -4 Step drill 100 Degree Countersink Bit Rivet Gun or Rivet Squeezer SK-4P3 Pliers SK-T26 Grommet Retainer Installation Tool Template-245A Optional Drill Jig – 1-1/4” Hole Saw and ¾” Hole Saw Before you begin – Take a close look at your cowling before removal. Note its positioning relative to the prop spinner. If the cowling appears to not align with the spinner bulkhead or is not centered, repositioning of shims and mounts can correct this problem. Also note clearances between the aft cowling skin and the fuselage skin. The allowable gap is 0.03 inch to 0.25 inch, with 0.12 inch preferred, except within 5.0 inches above and below the static port where the allowable gap is 0.06 inch to 0.13 inch. With this installation, it is simple to correct a side fastener alignment problem by a shim adjustment when you install the new SK2003 mounts, and positioning adjustment (alignment) of the mount to correspond with fastener hole in the cowling and or centering of the nose of the cowl. *Note paint stripes and paint lines. If the airplane was repainted with old mounts, new mounts made by Lord® or Skybolt® will alter these lines. Camwashers can fix this issue. Note any difficulty of fasteners aligning with respective holes. To do this conversion correctly, we will address all of these issues. Many cowlings are difficult to install because of unaligned side holes and fasteners, especially the rear most fasteners. A shim adjustment (firewall platemounts) can cure this problem easily. If your cowling has no problems with skin clearance or side fasteners, thus shim adjustments are not necessary, the next step is to note any adjustments required to center the nose of the cowling relative to the spinner. If shim adjustments are required, mount alignment will become more of a two-step process involving both the upper and lower cowling. By moving Skybolt Copyright 2016 Page 5 of 13 November 1, 2016 the mounts forward or rearward, the nose cowling can be adjusted. The second step will be to adjust firewall mounts in order to center the fastener hole with the corresponding mount. With the SK2003-AW4 washers, this adjustment is very easy. Step 1 – (1/2 Hour) Place 8” strips of 1” masking tape behind the rivet line on the boot cowl adjacent to each stud as noted in picture. Sight template over each stud and mark holes onto tape. This important step will greatly enhance the alignment of each SK2003 mount at each location. Close-up of template placed over stud and holes marked for alignment after cowling removed Now, when you remove the cowling, it is easy to determine the mount position relative to the cowling hole for each location. If the template determines that a mount is over 1/4” from the center, the use of SK2003-AW4 Cam Washers are an easy fix to re-locate the new mounts. This is all too common on many Cessna cowling mounts. Without the SK203-TEM1, it would be difficult to tell just how much each mount is off from its respective cowling hole. To move a mount far enough to center (as in this case), this mount will need to be modified for SK2003- AW4 Camwashers. With camwashers installed, simply dial the washer to move the mount until centered with the template. It is that simple! We will discuss the camwashers later on page 7. Figure 1 Figure 2 Figure 3 Skybolt Copyright 2016 Page 6 of 13 November 1, 2016 Step 2 - Remove Upper Cowling (Leave Lower Cowling on Aircraft). If you are not converting the side fasteners, place a piece of tape over the rear hole of the side cowling to prevent drilling in Step 5. Step 3 – (1/2 Hour) Remove Old Upper Firewall Platemounts Note the number of shims at each location and mark this on the firewall bracket. Plan to add or subtract shims to achieve clearances stated in Step 1. Now, remove all old mounts. Step 4 – (1/2 Hours) Install New SK2003-42 Platemounts Install new SK2003-42NR Mounts at all upper firewall locations with hardware supplied in kit. With the SK203- TEM1 template, check that each mount is centered as described above. If mounts are not centered within 1/4 of an inch, the SK2003-AW4 Camwashers must be considered. Step 5 - (1/4 Hour) Upper Cowl Firewall Holes Only (For Firewall Only Kits, do not drill rear hole along cowling Side) - With Unibit-1, drill firewall mount fastener holes to 15/32 (the next to last step on the Unibit-1 drill). Step 6 – (1/4 Hour) Install Grommets Install the grommets and retainers with the SK-T26 tool. Push the R4G retainer onto the tapered shank close to the end, then use the hand tool to insert the ring onto the grommet. Check that the retainer is properly seated. Step 7 – Install CLoc® Studs in firewall holes in Upper Cowling with SK-4P3 Pliers. Step 8 – (1/4 Hour) Position Upper Cowling. Lock firewall studs and note any changes to the alignment of the side fasteners. (With new mounts, most likely you will see alignment issues). This step will determine the decision to use SK2003-AW4 CamWashers for the Lower Cowling Mounts. You now have a good baseline to work with the Lower Cowling. Step 9 - Remove Upper Cowling Step 10 – (1/2 Hour) Remove Southco Receptacles from Lower Cowling sides – Drill out Southco receptacles with #40 drill. Step 11 – Remove Lower Cowling Step 12 – (1/2 Hour) Lower Firewall - Remove Old Firewall Platemounts as noted in Step 3. Figure 4 Skybolt Copyright 2016 Page 7 of 13 November 1, 2016 Step 13 – (1/2 Hour) Install New SK2003-42 Platemounts Install new SK2003-42A Mounts at all lower firewall locations with hardware supplied in kit. With the SK203- TEM1 template, check that each mount is centered as described above. If mounts are not centered within 1/4 of an inch, the SK2003-AW4 Camwashers must be considered. Step 14 – (1/4 Hour) With Unibit-1, drill Lower Cowl firewall mount fastener holes to 15/32 (the next to last step on the Unibit-1 drill). Step 15– (1/4 Hour) Install Grommets in Lower Cowling firewall as described in Step 6. Step 16 – Install 2ea CLoc® Studs in upper firewall holes in Lower Cowling with SK-4P3 Pliers. (Leave the other studs out for the initial phase). Note – We are purposely not installing any side receptacles until Step 22. Step 17 – (1/2 Hour) Position Lower Cowling and fasten two upper fasteners to hold cowling in place. Be certain that rear cowling firewall doubler (doubler inside of Lower Cowling) is properly positioned on mounts. Note 3 things: (1) Do the cowling paint stripes line up. (2) Is the cowling in line with the spinner? (3) Look through each grommet hole to determine if mounts are aligned with holes. Placing the Upper Cowling into position will also determine how close the horizontal split is a proper fit. It is more of the norm that 2-3 mounts do not align with the grommet holes; that the paint stripe is not aligned; and the horizontal split is ¼ inch or more from an ideal fit. You can force anything up to a point, but the beauty of this installation is that we can fix all of these problems with shims and/or the SK2003-AW4 Camwashers. Note: If by chance your cowling holes all align; the paint stripes align; and the horizontal split holes all align, skip to step 20. This is a rare occurrence. If the lower cowling must be shifted up (typically), consider removing shims at the bottom. If shim elimination is not an option, plan on using SK2003-AW4 Camwashers at multiple locations on either side of the lower cowling. By “dialing” the Camwashers full up for multiple mounts, the cowling can be shifted up considerably without the cowling skin touching the aircraft skin. Approximately .030 clearance can be considered a minimum. You may find that only one side needs a shift. Skybolt Copyright 2016 Page 8 of 13 November 1, 2016 ----------------If Required--------------- Step 18 – (1 Hour) To modify SK2003-42 Mounts - If Required Typically, three or four mounts may require movement greater than 1/4 of an inch. Modify as many SK2003 mounts as required by drilling mounting holes to 7/16 inch with a Unibit-1 bit. Deburr holes and check that the SK2003- AW4 washers insert properly. Drill mount holes to 7/16” with Unibit-1 drill Modified SK2003 Platemount installed with SK2003-AW4 Cam Washers. Simple Drill Jig - Use a small 2x4 as a drill fixture. Trace a platemount onto the wood surface. Mark the mount center and the center for each mounting hole. Drill the center all the way through the board with a 1-1/4” hole saw. For the “ears”, only plan to drill the mounting holes ¼” deep. Any deeper and a typical drill press with a Unibit-1 will use up its full stroke prior to the 7/16 step. Use a ¾” hole saw for the ears. Carefully notch the wall between the large and small holes so that the mount fits nicely into the drill jig. Place the mount into the drill jig and drill each mounting hole. To prevent a huge burr on the back side, only start the 7/16” step less than ½ way through the metal and stop. Flip the mount and finish the 7/16” step from the back side. The SK2003-AW4 Cam Washers are slotted so as the mounts can be fastened in a centered position. (Previous versions had no center positioning). By moving the mount within the slot, centering may be possible. For additional movement, simply rotate the washers to a desired center or shift. Once the desired center or shift is located, tighten screws and you are done. Unlike the Cessna Service Bulletin SB98-53-02, this modification is easy, accurate, and involves no drilling of the airframe brackets or relocation of brackets. Figure 5 Figure 6 Figure 7 Skybolt Copyright 2016 Page 9 of 13 November 1, 2016 Note – Camwashers “dialed” full up to shift this Lower Cowl up to the paint line and to align side fasteners. The 3 lower mounts on the right side have all been modified for the SK2003-AW4 Camwashers, full up bias. The left side of this cowling did not need this shift for alignment Step 19 – (1 Hour) Re-install modified SK2003-42A Mounts. “Dial” the Camwashers to the desired offset to achieve alignment goals. Step 20 – (1/2 Hour) Position Lower Cowling as described in Step 17. Position the Upper Cowling. Install SK40S5S fasteners in all firewall holes and lock. (Note: If studs appear to be tight or not lock, do not force to lock. A longer stud is required). Now note 3 things: Are the same alignment items as described above resolved? Hopefully, considerable progress has been made. The horizontal split holes should be close to center, hopefully, at center. If alignment is still a problem, additional Camwashers may be the only answer. With Lower Cowl fastened, and Upper Cowl in position, stripes are in line, side edge is properly positioned with paint line, and side holes are in line. Figure 8 Figure 9 Skybolt Copyright 2016 Page 10 of 13 November 1, 2016 At this point, all firewall mounts are properly positioned and all firewall studs are properly locked. All horizontal holes are aligned. If any alignment issue remains, the quality of this conversion assumes that these conditions are addressed and resolved. On some cowlings, this can be time consuming and outside of the estimate of time required to fix. *Step 21 – (1/4 Hours) Establishing desired center for all Side Receptacles. With both cowlings properly positioned and firewall fasteners properly locked, the desired positioning of each side receptacle can be easily established by marking or scribing each side hole through the grommet. Remove the Upper Cowling. Check that the scribe lines are within reasonable location to the original center holes. The SK245-461 has 1-1/4” rivet spacing to allow slight offsets and no interfere with the previous rivet holes. Note: The kit includes 1 SK244-461 Cage to use as a drill template. *Step 22 – (1 Hour) With Lower Cowling on aircraft, determine that the SK245-461A Receptacle Assemblies will fit within the limits of the inner doubler and the cowling edge. Some cowlings may require a slight trim of the angle doubler on the lower right side, rear most hole. Clamp the template (SK244-461 Cage), centered to the scribe marks. With Unibit-3 or -4 Stepdrill, expand the center pilot holes to 5/8”. Drill outer rivet holes with #30 drill. Repeat this procedure for all side holes. Countersink all rivet holes and deburr all holes. *Step 25 – (1/2 Hour) Mount all SK245-461A side receptacle assemblies as shown. Figure 10 Note that the locking clip engagement tab is mounted upwards (accessible). See Figure 12. Note: This photo is of previous mount receptacles Skybolt Copyright 2016 Page 11 of 13 November 1, 2016 *Step 26 – (1/2 Hour) Position Top Cowling. Lock all firewall fasteners. Install SK40S5 studs along sides and lock. Studs should lock with heads flush with grommet face. Step 27 – (1/2 Hour) Install Lower and Upper Cowl. Lock all studs around firewall. Begin engaging studs along the sides and continue to turn until adjusted so that the stud head is flush with the grommet face. With a sharp push-turn motion, attempt to unlock studs without disturbing the receptacle insert. Remove Upper Cowl. Pull anti-lock pins. With a flat blade screwdriver, turn inserts so that the slot is just past being aligned with the mounting rivets Re-Adjusting the SK245-461A Adjustable Receptacle (after initial adjustment and pin removal) The easiest method of re-adjustment is with a curved pick tool (part of any pick tool set). It allows access in tight spaces and is much easier to use than a straight pick tool. Locate the locking clip tab (the reason we orientated the receptacle in Step 25). Insert the pick and lift the tab, unlocking the insert, adjust with flat blade screwdriver. One half turn adjusts the fastener .015; one full turn adjusts the fastener .030; the equivalent of a stud dash number. Figure 11 Figure 12 Skybolt Copyright 2016 Page 12 of 13 November 1, 2016 Platemount Configured Aircraft Screw Platemount Aircraft Note Year Models Serial Numbers Cowlings Cowlings C150 A 59-66 150A-F 17001-17999, 5901-64532 6,527 C150 1 67 On 150G-M 64533 thru 79405 14,872 A150 1 70-77 150K-M A150001 thru A150734 734 C172 A 56-66 172, A-G 28000-54892 plus Reims SN 27,279 C172 1 67-81 172H-P 54893 thru 75034 21,186 C172 2 82-83 172P 75035 thru 76079 200 C172 2 83 172Q 75869 thru 76079 200 C172 3 84-86 172PII & Q 76080 thru 76673 593 C172 4 77-81 172XP,XPII 2000 thru 3454 1,454 C172 5 96-On 172 R&S 300 C175 A 58-62 175, Skylark 55001 thru 57119 2,119 C177 1 71-78 177 A-B Classic 0001 thru 1366 2,752 C177RG 1 71-78 177RG,RGII 0001 thru 1366 1,366 C180 A 53-60 180, A-C 30002-33000, 50105-50911 3,804 C182 A 56-60 182, Skylane 33000 thru 53007 4,105 C182 5 73-86 182P-RB 61426 thru 68542 7,116 43,834 50,773 Note Configuration A Screw Cowling (1) Lord-Southco (2) Lord-Southco FW & Sides, Camloc 4002 Nose (3) Lord-Camloc 27S3 FW & Sides, Camloc 4002 Nose (4) Lord-Southco FW, Camloc 4002 Top Center, Nose & Sides (5) Lord-Camloc 27S3 FW, Camloc 4002 Sides Weight & Balance Considerations for Conversion Original Skybolt Aircraft Fasteners Fasteners C150 .160g/.35lb .385g/.85lb C172 .210g/.46lb .525g/1.15lb C177 .215g/.48lb .520g/1.15lb C182 .170g/.37lb .385g/.85lb Skybolt Copyright 2016 Page 13 of 13 November 1, 2016 Proper Installation of this modification is important. Equally important is proper documentation. Before returning your aircraft to service, you must accomplish 3 important steps: 1) Send Email to Skybolt to receive a copy of this STC, authorization to use the STC, and accepted language to file Form 337 with the FAA 2) *Prepare and file Form 337 with the FAA. Note: as this is an STC’d installation; Form 337 is filed after the conversion is complete and no further acknowledgement from the FAA is required. But it must be filed for the aircraft to be returned to service. 3) Make a logbook entry that the kit was installed as per the Skybolt Instructions (Rev number/Date). By contacting Skybolt (dbowers@skybolt.com or abraun@skybolt.com) this allows us to log and track the airframe that has been converted. If we have a revision to our kit or any issues with any component of the kit, we will have a method to contact the owner with important details. Please provide the following: 1) N Number of the aircraft 2) Model and Serial Number of Aircraft 3) Kit Serial Number 4) Date of Purchase 5) From whom Purchased 6) Date of Installation 7) Engine – O360 Yes/No 8) Approximate hours on engine and/or engine mounts