# AD 70-16-05: Engine Exhaust Muffler - Type: Airworthiness directive - Status: Current - Products: Piper PA-28-140, PA-28-150, PA-28-160, PA-28-180, PA-28S-160 and PA-28S-180 - Effective: May 19, 1972 - Published: May 13, 1972 - Issued: May 1, 1972 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Small airplane - Amendment: 39-1446 - Registered aircraft: 8,139 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/309FA53AFC0BE91886256E01005ACA2C.0001 - DRS record last changed: November 21, 2025 - Page: https://openairdocs.org/ad/70-16-05 ## The airworthiness directive 70-16-05 PIPER: Amdt. 39-1057 as amended by Amendment 39-1446. Applies to the following Model PA-28 airplanes equipped with Piper muffler Part Number 63627-00 or 63688- 00: (a) PA-28-140 airplanes having Serial Numbers 28-20001 through 28-26400 (b) PA-28-150, PA-28-160, PA-28S-160, PA-28-180, PA-28S-180 airplanes having Serial Numbers 28-03, 28-1 through 28-1760A. Compliance required as indicated. To prevent failure of the engine exhaust muffler, accomplish the following: (a) For those airplanes which have mufflers with 950 or more hours time in service on the effective date of this airworthiness directive, unless already accomplished comply with paragraph (c) within the next 50 hours time in service and thereafter at intervals not to exceed 50 hours time in service from the last inspection. (b) For those airplanes which have mufflers with less than 950 hours time in service on the effective date of this airworthiness directive, unless already accomplished, comply with paragraph (c) within the next 50 hours time in service, and thereafter at intervals not to exceed 100 hours time in service from the last inspection. After the muffler has accumulated 950 hours time in service, comply with paragraph (c) at intervals not to exceed 50 hours time in service from the last inspection. (c) Inspect the muffler for signs of cracks, burn-throughs, weld separations, failed internal baffles, and general condition. Remove the muffler assembly by disconnecting air ducts, stacks, shrouds, as necessary to permit a thorough visual inspection of the exterior and interior surfaces with a probe light and mirror. The cabin air heat shroud must also be removed from the muffler. Except during the initial inspection the muffler need not be removed from the airplane, provided visual inspection with probe light and mirror is made through the tailpipe and through one end at the stack connection. Additional information will be found in Advisory Circular 43.13-1, Chapter 14, Section 3. (d) Mufflers found damaged or deteriorated as described above must be replaced or repaired before further flight. Thereafter comply with the inspection requirements of paragraph (a) or (b), whichever is applicable. Repairs may be made by welding in accordance with Advisory Circular AC 43.13-1, Chapter 2, Section 2, or an FAA-approved equivalent. After welding, accomplish a submerged pressure check at 10 psi air pressure. Leaks are not permissible. Do not re-install mufflers having loose, broken, or missing internal baffle tubes. Care should be exercised when re-installing the exhaust system components to prevent distortion or preloading of parts. (e) The inspection time intervals may be adjusted up to a maximum of 10 hours to coincide with airplane annual or 100 hour scheduled inspections. (f) The recurrent inspections required in paragraphs (a) and (b) may be discontinued upon installation of the new improved muffler as follows: (1) Piper Part No. 99482-00 on Model PA-28-140, PA-28-150, PA-28-160, and PA-28S-160. (2) Piper Part No. 99482-02 on Model PA-28-180 and PA-28S-180. (3) Or other equivalent muffler installations approved by the Chief, Engineering and Manufacturing Branch, Federal Aviation Administration, Southern Region. Amendment 39-1057 became effective August 10, 1970. This amendment 39-1446 becomes effective May 19, 1972. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS 2A13](https://openairdocs.org/tcds/2A13): Piper Aircraft Inc.; names 6 of 18 models: PA-28-150, PA-28-140, PA-28S-160, PA-28-160, PA-28S-180, PA-28-180 ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 8,139 (8,139 by airframe model, 0 by engine model) - Makers: Piper 8,139 Models with the most aircraft: - [Piper PA-28-140](https://openairdocs.org/model/piper-pa-28-140): 4,258 aircraft (airframe model) - [Piper PA-28-180](https://openairdocs.org/model/piper-pa-28-180): 3,504 aircraft (airframe model) - [Piper PA-28-160](https://openairdocs.org/model/piper-pa-28-160): 253 aircraft (airframe model) - [Piper PA-28-150](https://openairdocs.org/model/piper-pa-28-150): 123 aircraft (airframe model) - [Piper PA-28S-180](https://openairdocs.org/model/piper-pa-28s-180): 1 aircraft (airframe model) All 5 models: https://openairdocs.org/ad/70-16-05/models.md Every aircraft: https://openairdocs.org/ad/70-16-05/aircraft.md ## Related documents - [AC 43.13-1B CHG 1 Ed Update](https://openairdocs.org/ac/43.13-1): Acceptable Methods, Techniques, and Practices—Aircraft Inspection and Repair. Cited as AC 43.13-1 in the AD's requirements ## NTSB investigations that cite this AD (2) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB FTW99LA036](https://openairdocs.org/ntsb/FTW99LA036), Nov 25, 1998: Piper PA-28-160 (N5087W), Greenville, TX, minor damage. Probable cause: The partial loss of engine power due to a blocked muffler exhaust pipe/manifold as a result of a loose internal baffle. Factors were the improper maintenance by other maintenance personnel and the… - [NTSB FTW84LA141](https://openairdocs.org/ntsb/FTW84LA141), Feb 20, 1984: Piper PA-28-140 (N15043), Bastrop, TX, substantial damage --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.