# AD 71-17-05: Main Rotor Mast

- Type: Airworthiness directive
- Status: Current
- Products: Brantly International B-2, B-2A and B-2B
- Effective: November 26, 1971
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Amendment: 39-1339
- Registered aircraft: 53 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/F40278BEE92D883786256E01005AD4B2.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/71-17-05

## The airworthiness directive

71-17-05 BRANTLY ROTORCRAFT: Amdt. 39-1267 as amended by Amendment 39- 1339. Applies to B-2, B-2A, and B-2B type rotorcraft certified in all categories.

Compliance required within the next 10 hours time in service after the effective date of this airworthiness directive and every 50 hours time in service thereafter.

To preclude the possibility of impairing the structural integrity of the main rotor mast P/N 104-1, due to corrosion, accomplish the following:

a. Remove mast plug P/N 151-18.

b. Visually inspect the inner bore surface over the entire length of main rotor mast for presence of rust or corrosion using a light and mirror. The presence of any rust or corrosion which cannot be removed with a lint free cloth is cause for removal of the transmission assembly.

c. Prior to reinstallation or replacement, accomplish the 1200 hour interval inspection in accordance with Brantly Maintenance Manual, Section 1.8.7.

d. If the main rotor mast is free or can be freed of rust or corrosion following the inspection noted in paragraph (b), apply a thin film of Spec. Mil.-C-6925C preservative type lubricating oil to the entire length of the inner bore surface. Reinstall the mast plug with a new "O" ring packing P/N AN 6227-62. Install the plug and retain it in place with the same clevis pin, P/N AN 393-11 that retains hub retaining nut, P/N 150-1. Secure the clevis pin by installing washer, P/N AN960-10L and cotter pin P/N AN-380-2-1.

e. Safety wire bolt, P/N 151-8 to hub retaining nut.

f. Upon submission of substantiating data by an owner or operator through an FAA Maintenance Inspector, Chief, Engineering & Manufacturing Branch, FAA, Eastern Region, may adjust the repetitive inspection interval specified in this airworthiness directive. Equivalent inspections must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region.

Amendment 39-1267 was effective August 19, 1971. This amendment 39-1339is effective November 26, 1971

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 2H2](https://openairdocs.org/tcds/2H2): Brantly International Inc.; names 3 of 3 models: B-2B, B-2A, B-2

## 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: 53 (53 by airframe model, 0 by engine model)
- Makers: Brantly 53

Models with the most aircraft:

- [Brantly B-2B](https://openairdocs.org/model/brantly-b-2b): 34 aircraft (airframe model)
- [Brantly B-2](https://openairdocs.org/model/brantly-b-2): 17 aircraft (airframe model)
- [Brantly B-2A](https://openairdocs.org/model/brantly-b-2a): 2 aircraft (airframe model)

All 3 models: https://openairdocs.org/ad/71-17-05/models.md
Every aircraft: https://openairdocs.org/ad/71-17-05/aircraft.md

Its text cites no advisory circulars or STCs.

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