AD 67-14-07 ACTIVE

67-14-07 PIPER: Amdt. 39-375 Part 39 Federal Register April 20, 1967. Applies to Model PA-25-235 Airplanes, Serial Numbers 25-2000 to 25-4171 Inclusive.

Compliance required as indicated.

To prevent further failures of engine exhaust system components, accomplish the following:

(a) Initial Inspection.

Unless already accomplished, conduct the following inspections within the next 50 hours' time in service after the effective date of this AD on aircraft with 150 or more hours total time. On aircraft with less than 150 hours' total time, conduct the following inspection before an accumulation of 200 hours' total time unless already accomplished.

(1) Inspect the entire exhaust system for signs of cracks, burn-throughs, weld separations, failed internal baffles, etc. Remove the muffler assembly by disconnecting air ducts, stacks, shrouds, etc., as necessary to permit a thorough visual inspection of exterior and interior surfaces with a probe light and mirror. The cabin air heat shroud must also be removed from the muffler.

(2) In addition to the exhaust inspection, accomplish the following:

(i) Inspect the lower ignition harness for deteriorated insulation.

(ii) Inspect the lower engine mount in the area near the exhaust stack for blistered or burned paint and rust.

(iii) Inspect the rubber engine mount bushings for deterioration and loss of resilience.

(iv) Inspect all flexible air and heat ducting for deterioration and burning.

Parts bound damaged or deteriorated as described above must be replaced or repaired before further flight.

Extreme care must be exercised when re-installing the exhaust system components to prevent distortion of preloading any parts.

(b) Recurrent Inspections.

With 50 hours' time in service from the initial inspection and every 50 hours' time in service thereafter, repeat the initial exhaust system inspection described in (a)(1) except that the muffler neednot be removed from the aircraft provided visual inspection with probe light and mirror are made through the muffler tail pipe outlet and one end of the muffler at the stack connection.

(c) Compliance Time Adjustments.

(1) The inspection time intervals may be adjusted up to a maximum of 15 hours to coincide with aircraft annual or 100 hour scheduled inspections.

(2) Inspections, repairs or alterations must be accomplished by authorized individuals or repair facilities. Aircraft log record entry must be made to reflect AD compliance in accordance with FAR 91.173.

(d) The recurrent inspections of the exhaust systems as required in (b) may be discontinued upon installation of the new improved muffler and exhaust stack clamps included in muffler installation kit, Piper Part No. 753-753.

(Piper Service Bulletin No. 241 covers this same subject.)

This directive effective May 20, 1967.