A-94-149
NTSB Safety Recommendation — Aviation
Recommendation text
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: Issue an Airworthiness Directive to require that the input spiral bevel gear in the tail rotor drive shaft intermediate gearbox (P/N 204-040-003-37) on military surplus Bell Helicopter Textron UH-1 and TH-1 series helicopters involved in repeated heavy lift operations be periodically subjected to a magnetic particle (or equivalent) inspection of the gear teeth. Based on the failure history, the interval between inspections should be substantially less than 200 hours.
In plain language (FlightFinder summary)
The National Transportation Safety Board asks the Federal Aviation Administration to issue an Airworthiness Directive requiring periodic magnetic particle (or equivalent) inspections of the input spiral bevel gear teeth on a specific tail rotor drive shaft intermediate gearbox. The directive should apply to military surplus Bell Helicopter Textron UH-1 and TH-1 series helicopters used in repeated heavy lift operations, with inspection intervals set substantially below 200 hours based on past failures.
This plain-language summary is written by FlightFinder to explain the recommendation above. It is not the official wording — the verbatim NTSB text is quoted above.
Details
| Status | Closed - Acceptable Alternate Action |
|---|---|
| Mode | Aviation |
| Closed | Aug 29, 1995 |
| NTSB number | LAX94LA132 |
| Addressees | FAA |
External links
NTSB safety recommendations are advisory; addressees are not legally required to adopt them. Source: NTSB CAROL (public domain).