AD 57-22-01

57-22-01 PIPER: Applies to All Models PA-16, PA-20 and PA-22 Aircraft.

Compliance required as indicated.

To preclude the possibility of inflight fires the following inspection and rework is necessary to eliminate combustible material and possible ignition sources from the area aft of the firewall, underneath the forward cabin floor. Access to this section may be gained by removing the metal panels or opening the fuselage side cowl panels rearward of the firewall underneath the aircraft as shown in Piper Service Bulletin No. 161a. The relative difficulty in gaining access to this area has probably contributed to poor maintenance.

1. On all PA-16, PA-20, and PA-22 aircraft, Serial Numbers 22-1 through 22-2699, the following inspection and rework is necessary prior to December 15, 1957. Remove and discard any sound-proofing material contaminated with engine or hydraulic oil. Where the plastic septum has separated from the fiberglass or shows signs of drying or cracking it should be removed in its entirety from the affected blanket. Uncontaminated fiberglass, from which the plastic septum has been removed, may be continued in service. Inspect electrical wiring for chafing of the insulation and replace any found in an unsatisfactory condition. Check for a reasonable clearance between hydraulic lines, electrical wires, control cables and fuel lines and rework as necessary. The sealing of the firewall on all affected aircraft must be inspected as described in Piper Service Bulletin No. 161a and when found deficient must be resealed in accordance with the manufacturer's service bulletin or accepted aeronautical practices.

2. On PA-22 aircraft Serial Numbers 22-2700 to 22-6194 inclusive, the procedure outlined in 1 should be followed within the next 100 hours of operation.

3. Periodic inspection should be made of the exhaust system in accordance with Piper Service Bulletin No. 161a pertaining to inspection of the exhaust stack gaskets,exhaust stacks, muffler assembly, and muffler tailpipe.

4. The sealing of the firewall on all PA-16, PA-20 and PA-22 aircraft must be inspected at 100-hour intervals in accordance with Piper Service Bulletin No. 161a. If found deficient, it must be resealed in accordance with the manufacturer's service bulletin or accepted aeronautical practices.

5. The 100-hour inspection requirement on all Model Piper PA-22 aircraft, Serial Numbers 22-1 to 22-6194 inclusive, can be eliminated if Piper Kit, P/N 754237 or equivalent, is installed.