A-87-029
NTSB Safety Recommendation — Aviation
Recommendation text
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: ISSUE AN AIRWORTHINESS DIRECTIVE TO REQUIRE INSPECTION DURING THE NEXT OVERHAUL OF THE MAIN TRANSMISSION, OF HUGHES 500D (MCDONNELL DOUGLAS HELICOPTER MODEL 369) AIRCRAFT WITH P/N 369D25125, MAIN TRANSMISSION OUTPUT PINION GEARSHAFTS, TO (1) IDENTIFY PINIONS MANUFACTURED WITH SIMPLE JOURNAL-TO-SHOULDER FILLET RADII; (2) INSPECT FOR CRACKS IN THE RADII OF THESE PINIONS; (3) REMOVE ANY CRACKED PINIONS IMMEDIATELY FROM SERVICE; AND (4) REWORK ANY UNCRACKED PINIONS WITH SIMPLE FILLET RADII TO THE 0.05 TO 0.07 INCH UNDERCUT RELIEF RADIUS AND SHOT PEEN AS REQUIRED BY HUGHES ENGINEERING ORDERS 135599 AND 135600, RESPECTIVELY.
In plain language (FlightFinder summary)
The FAA is asked to issue an airworthiness directive requiring that during the next overhaul of the main transmission on Hughes 500D (McDonnell Douglas Model 369) helicopters with part number 369D25125, operators identify output pinion gears with simple journal-to-shoulder fillet radii, inspect those pinions for cracks, remove any cracked pinions, and rework uncracked pinions by adding an undercut relief radius and shot peening per specified engineering orders.
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 | Nov 5, 1987 |
| NTSB number | BFO86FA018 |
| Addressees | FAA |
External links
NTSB safety recommendations are advisory; addressees are not legally required to adopt them. Source: NTSB CAROL (public domain).