# AD 73-14-02: Cracks in Exhaust System

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-34-200
- Effective: June 29, 1973
- Published: June 21, 1973
- Issued: June 11, 1973
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-1673
- Registered aircraft: 172 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/C782FDC3054F02B2862569990050FC15.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/73-14-02

## The airworthiness directive

73-14-02 PIPER: Amdt. 39-1673. Applies to PA-34-200 airplanes, Serial Numbers 34-E4 and 34-7250001 and up equipped with exhaust systems Piper Part Numbers 96465-00 and 96466-00.

Compliance required within the next 10 hours time in service after the effective date of this AD or before the accumulation of 60 hours time in service whichever occurs later and thereafter at intervals not to exceed 25 hours time in service from the last inspection.

To insure that cracks are not present in the exhaust system, accomplish the following:

  (a) Remove both right and left nose cowls, Piper Part Numbers 96500-34 and 96500-35, and open both right and left cowl doors on both right and left engines. Inspect the entire exhaust system for any evidence of cracks or failed ducts or flanges. Use an inspection mirror as required, a minimum 100 watt light and a minimum four power magnifying glass.

  (b) If the exhaust systems are found to contain cracked or broken ducts, flanges or parts, replace with new replacement parts or repair the affected parts in accordance with Advisory Circular 43.13-1 before further flight.

Piper Service Bulletin No. 373A pertains to this subject.

This supersedes amendment 39-1564 (37 F.R. 25221) AD 72-25-01.

This amendment becomes effective June 29, 1973.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A7SO](https://openairdocs.org/tcds/A7SO): Piper Aircraft Inc.; names 1 of 5 models: PA-34-200 (Seneca)

## 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: 172 (172 by airframe model, 0 by engine model)
- Makers: Piper 172

Models with the most aircraft:

- [Piper PA-34-200](https://openairdocs.org/model/piper-pa-34-200): 172 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/73-14-02/models.md
Every aircraft: https://openairdocs.org/ad/73-14-02/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

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