A-91-019
NTSB Safety Recommendation — Aviation
Recommendation text
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: ISSUE AN AIRWORTHINESS DIRECTIVE APPLICABLE TO ATR 42 AIRPLANES TO REQUIRE INITIAL AND PERIODIC VISUAL INSPECTIONS OF THE SEALANT AROUND THE SPHERICAL BEARINGS AT THE BOTTOM END OF THE LANDING GEAR SIDE BRACE ASSEMBLY LOWER ARMS (P/N D56779) FOR CRACKING OR DAMAGE. THE THRESHOLD FOR THE INITIAL INSPECTION AND THE PERIODIC INTERVALS SHOULD BE SUBSTANTIALLY LESS THAN 10,000 CYCLES. LOWER ARMS THAT CONTAIN CRACKS OR DAMAGE IN THE SEALANT SHOULD BE IMMEDIATELY INSPECTED BY ULTRASONIC METHODS AS DESCRIBED IN ATR SERVICE BULLETIN NO. ATR42-32-0036 AND MESSIER BUGATTI SERVICE BULLETIN NO. 631-32-070. HOWEVER, THE REJECTION LIMIT FOR THE ULTRANSONIC INSPECTION SHOULD BE SUBSTANTIALLY REDUCED FROM THAT SPECIFIED IN THE SERVICE BULLETINS. THE AIRWORTHINESS DIRECTIVE SHOULD ALSO ESTABLISH AN APPROPRIATE PERIODIC ULTRANSONIC INSPECTION INTERVAL FOR THOSE LOWER ARMS THAT PASS THE INITIAL ULTRASONIC INSPECTION. (URGENT)
In plain language (FlightFinder summary)
The Federal Aviation Administration must issue an airworthiness directive for ATR 42 airplanes to require initial and periodic visual inspections of sealant around specific spherical bearings on the landing gear side brace lower arms, with inspection intervals substantially less than 10,000 cycles. Lower arms with cracked or damaged sealant need immediate ultrasonic inspection per specified service bulletins, but with a substantially reduced rejection limit. The directive should also set periodic ultrasonic inspection intervals for lower arms that pass the initial ultrasonic check.
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 | Feb 10, 1994 |
| NTSB number | MIA91IA032 |
| Addressees | FAA |
External links
NTSB safety recommendations are advisory; addressees are not legally required to adopt them. Source: NTSB CAROL (public domain).