# AD 60-07-06: Landing Gear Lock Plunger

- Type: Airworthiness directive
- Status: Current
- Products: Martin-Marietta 404
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Registered aircraft: 5 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/736564D614252E7C86256A32005BD201.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/60-07-06

## The airworthiness directive

60-07-06 MARTIN: Amdt. 118 Part 507 Federal Register March 25, 1960. Applies to All Model 404 Aircraft.

Compliance required as indicated.

Investigation of a recent Model 404 wheels up landing disclosed that the landing gear lock linkage and lock plunger malfunctioned. Inspection of the jury strut revealed that when the lock plunger was pulled back to normal travel limits in operating the "free fall" actuating mechanism to "full travel", the plunger would periodically jam in the retracted position and consequently flare out in the form of a knife edge. Also, cutting action was evident in the forward bushings (in the plunger cylinder) in an area coincident with the two flared edges. To prevent further lock plunger malfunctioning, the following must be accomplished:

  (a) Replace lock plunger P/N 404-4088121-3 with new lock plunger P/N 404- 4900121-5 on each main landing gear by July 31, 1960.

  (b) At each 320 hours' time in service commencing not later than May15, 1960, visually inspect main and nose gear lock plungers for a spalling or flaring condition. Check the lock plunger for free operation. The plunger should be free from dirt, dust, moisture, ice, etc. If spalling or flaring exists, the lock plunger must be chamfered (rounded out) at the corners of the plunger for the full length of the flat area.

(Martin Service Bulletin No. 404-260 dated October 30, 1952, partially covers this subject.)

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1A7](https://openairdocs.org/tcds/1A7): Martin-Marietta Corporation; names 1 of 1 models: 404

## 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: 5 (5 by airframe model, 0 by engine model)
- Makers: Martin 5

Models with the most aircraft:

- [Martin 404](https://openairdocs.org/model/martin-404): 5 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/60-07-06/models.md
Every aircraft: https://openairdocs.org/ad/60-07-06/aircraft.md

Its text cites no advisory circulars or STCs.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.