A-94-189
NTSB Safety Recommendation — Aviation
Recommendation text
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: ISSUE AN AIRWORTHINESS DIRECTIVE FOR HILLER AIRCRAFT HELICOPTER MODELS UH-12A THROUGH -12E, OH-23D, OH-23F, OH-23G, AND ALL HILLER HELICOPTER MODELS CONVERTED BY SUPPLEMENTAL TYPE CERTIFICATES 178WE AND 177WE TO REQUIRE THAT P/N 51452, P/N 51414-1, AND P/N 51435 OUTBOARD TENSION-TORSION (T-T) BAR PINS BE INSPECTED BY DYE PENETRANT METHOD FOR CRACKS IN THE AREA OF THE BOLT THROUGH-HOLE AT 100-HOUR INTERVALS. T-T BAR PINS FOUND TO CONTAIN A CRACK SHOULD BE REPLACED WITH AIRWORTHY PARTS. THE AIRWORTHINESS DIRECTIVE SHOULD REQUIRE CHECKING AND ADJUSTING THE ALIGNMENT BETWEEN THE DRAG STRUT AND T-T BAR PINS AND INSTALLING SHIMS AT THE INBOARD DRAG STRUT TERMINAL LOCATION ACCORDING TO THE HILLER SERVICE BULLETIN 51-9, APRIL 8, 1983.
In plain language (FlightFinder summary)
The Federal Aviation Administration is asked to issue an airworthiness directive covering several Hiller helicopter models, including UH-12A through -12E, OH-23D, F, and G, and those modified under supplemental type certificates 178WE and 177WE. The directive would require dye penetrant inspection of outboard tension-torsion bar pins (part numbers 51452, 51414-1, and 51435) for cracks around the bolt through-hole every 100 flight hours; cracked pins must be replaced. It would also mandate checking and adjusting the alignment between the drag strut and the tension-torsion bar pins, and installing shims at the inboard drag strut terminal as specified in Hiller Service Bulletin 51-9, April 8, 1983.
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 Action |
|---|---|
| Mode | Aviation |
| Closed | Aug 8, 1995 |
| NTSB number | LAX94LA054 |
| Addressees | FAA |
External links
NTSB safety recommendations are advisory; addressees are not legally required to adopt them. Source: NTSB CAROL (public domain).