# AD 77-13-06: Landing Flaps

- Type: Airworthiness directive
- Status: Current
- Products: Pilatus PC-6, PC-6-H1, PC-6-H2, PC-6/350, PC-6/350-H1, PC-6/350-H2, PC-6/A, PC-6/A-H1, PC-6/A-H2, PC-6/B-H2, PC-6/B1-H2, PC-6/B2-H2 and 2 more
- Effective: July 25, 1977
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-2928
- Registered aircraft: 11 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/AB725D7A6CD3E62586256A45006F9DE2.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/77-13-06

## The airworthiness directive

77-13-06 PILATUS AIRCRAFT LTD. AND FAIRCHILD HILLER: Amendment 39- 2928. Applies to Pilatus Model PC-6 airplanes (all variants) with serial numbers up through 743 and Fairchild Hiller Model PC-6 airplanes, serial numbers 2001 through 2019, 2021 through 2038, and 2040 through 2049, certificated in all categories. Compliance is required as indicated. To prevent a possible landing flap nose rib fatigue failure, accomplish the following: (a) Within the next 25 hours time in service after the effective date of this AD, unless already accomplished within the last 25 hours time in service, and, thereafter, at intervals not to exceed 100 hours time in service since the last inspection, visually inspect all the end ribs of the landing flaps for cracks in accordance with Pilatus Service Bulletin No. 124, paragraph 2.1, dated January 1976, or an FAA-approved equivalent. (b) If a crack is found during any inspection required by paragraph (a) of this AD, before further flight, repair the crack in accordance with paragraphs 2.1 and 2.2 of Pilatus Service Bulletin No. 124, dated January 1976, or an FAA-approved equivalent. (c) Within the next 1,000 hours time-in-service after the effective date of this AD, unless already accomplished, reinforce the landing flap nose end ribs in accordance with paragraph 2.3 of Pilatus Service Bulletin No. 124, dated January 1976, or an FAA-approved equivalent. (d) The repetitive inspections required by paragraph (a) of this AD may be discontinued after the reinforcement has been accomplished in accordance with paragraph (c) of this AD, and all cracks have been repaired in accordance with paragraph (b) of this AD. (Fairchild Hiller Service Bulletin PC-6-51-3 pertains to this same subject.) This amendment becomes effective July 25, 1977.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 7A15](https://openairdocs.org/tcds/7A15): Pilatus Aircraft Ltd.; names 14 of 15 models: PC-6/B2-H2, PC-6/350-H1, PC-6/C1-H2, PC-6/B-H2, PC-6/A-H2, PC-6/C-H2, PC-6, PC-6/A-H1…

## 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: 11 (11 by airframe model, 0 by engine model)
- Makers: Pilatus 11

Models with the most aircraft:

- [Pilatus PC-6/B2-H2](https://openairdocs.org/model/pilatus-pc-6-b2-h2): 8 aircraft (airframe model)
- [Pilatus PC-6/B1-H2](https://openairdocs.org/model/pilatus-pc-6-b1-h2): 2 aircraft (airframe model)
- [Pilatus PC-6](https://openairdocs.org/model/pilatus-pc-6): 1 aircraft (airframe model)

All 3 models: https://openairdocs.org/ad/77-13-06/models.md
Every aircraft: https://openairdocs.org/ad/77-13-06/aircraft.md

Its text cites no advisory circulars or STCs.

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