# AD 61-21-01: Tail Pipe Door

- Type: Airworthiness directive
- Status: Current
- Products: Bombardier CL-44D4
- Effective: October 17, 1961
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/4B5431A1C88B21F4862569A700581F32.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/61-21-01

## The airworthiness directive

61-21-01 CANADAIR: Amdt. 348 Part 507 Federal Register October 17, 1961. Applies to Model CL-44D4 Aircraft, Serial Numbers 14, 16, 19 through 23, 25 and 26.

Compliance required within the next 25 hours' time in service unless already accomplished within the last 10 hours' time in service and at intervals not to exceed 35 hours' time in service.

To preclude failure of the tail pipe door structure, the following must be accomplished:

  (a) Inspect the following tail pipe compartment access panels for fatigue cracking using dye penetrant or equivalent in the area of the attachment holes. Part Numbers to be inspected are 44-10721, 44-10721-1, 44-10722, 44-10722-1, 44-10726, 44-10721-990, 44- 10721-991, 44-10722-990, 44-10722-991, 44-10726-990, 44-10751, 44-10751-1, 44-10752, 44- 10752-1, and 44-10753.

  (b) If cracks are found, panels must be replaced, repaired or reinforced in accordance with Canadair Service Bulletin No. CL-44D4-138 or equivalent, or modified in accordance with a Department of Transport and FAA approved modification prior to further flight except ferry flight in accordance with the provisions of CAR 1.76. Following the incorporation of the interim repair or reinforcement covered in Service Bulletin No. CL-44D4- 138, or replacement, the inspections specified in (a) must be continued at intervals not exceeding 35 hours' time in service. If further cracks are found after repair or reinforcement per Canadair Service Bulletin CL-44D4-138, the parts shall be replaced or modified in accordance with Canadian Department of Transport and FAA approved modification.

  (c) The special inspections required by this airworthiness directive may be discontinued after incorporation of the Canadian Department of Transport and FAA approved modification of the affected parts.

  (d) Upon request of the operator, an FAA maintenance inspector, subject to approval of the Chief, Engineering and Manufacturing Branch, FAA Eastern Region, may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for such operator.

This directive effective October 17, 1961.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1A20](https://openairdocs.org/tcds/1A20): Bombardier Inc.; names 1 of 2 models: CL-44D4

## Registered aircraft it may apply to (OpenAirDocs)

No registered aircraft matched the models it names.

Its text cites no advisory circulars or STCs.

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