79-22-01 BELLANCA: Amendment 39-3596. Compliance is required within the next 30 days or 10 hours of aircraft time in service, whichever occurs first, after the effective date of this AD, unless already accomplished. To prevent exhaust system cracking, accomplish the following on Bellanca Model 7ECA (S/N 985-74 thru 1319-79), 8KCAB (S/N 120-74 thru 550-79 equipped with Lycoming AEIO-360 series engine), and 8GCBC(S/N 1-74 thru 323-79) aircraft:
1. Remove the upper and lower engine cowling.
2. Inspect exhaust system with particular attention to the welded area between the riser tube and the exhaust flange, for cracks, fractures or evidence of exhaust leakage. Remove the heater shroud and inspect the muffler body for cracks, fractures or evidence of exhaust leakage. If any exhaust system component is cracked or otherwise damaged, remove the exhaust system and repair/replace damaged parts in accordance with FAA Advisory Circular 43.13-1A.
3. Loosen exhaust port studnuts several turns; check bead clamps for tightness such that the clamps cannot rotate on the exhaust system with hand pressure. The riser flanges (1) must have equal spacing to the exhaust port pad at both studs (a small amount of flange bow is acceptable), (2) must be free to move up and down on the exhaust port studs without binding and (3) must all contact the exhaust port pads together.
4. If any of the alignment checks are unsatisfactory, determine the cause for the misalignment and repair or replace the part as required.
5. Assemble exhaust system and install on engine with loose exhaust port stud nuts and bead clamp bolts. Torque exhaust port stud nuts to the correct value. Tighten bead clamp bolts until clamps secure risers to exhaust system but allow clamps to rotate with hand pressure; the bead clamps should not be rigidly clamped to the tubes but should be able to rotate on the tubes with moderate hand pressure on the clamp assembly. NOTE: Torque all exhaust port stud nuts evenly and tighten bead clamp bolts evenly to insure uniform loads within the exhaust system parts; torquing bolts individually can cause very large stresses.
6. Inspect exhaust system for proper clearance between ducts, wiring, controls, etc. before reinstallation of the cowling. Install lower cowling and inspect for proper clearance between exhaust outlet and cowl.
7. Reinstall the lower and upper engine cowling.
Bellanca Service Letter Number C-138 covers this same subject.
Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Great Lakes Engine..
This amendment becomes effective October 29, 1979.