# AD 75-17-27: Main Rotor Head Assembly

- Type: Airworthiness directive
- Status: Current
- Products: Airbus Helicopters Deutschland BO-105A and BO-105C
- Effective: August 20, 1975
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Amendment: 39-2332
- Registered aircraft: 4 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/DBA76513664EBB6C86256A3A006D7508.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/75-17-27

## The airworthiness directive

75-17-27 MESSERSCHMITT-BOLKOW-BLOHM: Amendment 39-2332. Applies to Messerschmitt-Bolkow-Blohm (MBB) Models BO-105A and BO-105C helicopters, certificated in all categories, incorporating Main Rotor Head Assembly No. 105-14101. Compliance is required within the next 100 hours time in service after the effective date of this AD, unless already accomplished in accordance with MBB BO-105 Alert Service Bulletin No. 4 and Service Bulletin No. 10-11. To prevent development of incipient cracks, corrosion, and excessive wear on bolts of the main rotor head, accomplish the following: (a) For all Main Rotor Head Assemblies, P/N 105-14101, determine part number of Blade Mounting Bolts. If bolt P/N 105-14101.31 is found, replace with serviceable bolt of P/N 105-14101.29. (b) For Main Rotor Head Assemblies 105-14101 having Serial Number 50 or lower, determine part number revision letter of Main Rotor Bolts P/N 105-14101.22 and .23. If any bolt with revision letter "a" through "f" is found, replace with serviceable bolt of the same part number having revision letter "g" or subsequent. This amendment becomes effective August 20, 1975.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS H3EU](https://openairdocs.org/tcds/H3EU): Airbus Helicopters Deutschland GmbH (AHD); names 2 of 5 models: BO-105C, BO-105A

## 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: 4 (4 by airframe model, 0 by engine model)
- Makers: Messerschmitt-Boelkow-Blohm-Gm 4

Models with the most aircraft:

- [Messerschmitt-Boelkow-Blohm-Gm BO-105C](https://openairdocs.org/model/messerschmitt-boelkow-blohm-gm-bo-105c): 4 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/75-17-27/models.md
Every aircraft: https://openairdocs.org/ad/75-17-27/aircraft.md

Its text cites no advisory circulars or STCs.

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