A-70-028
NTSB Safety Recommendation — Aviation
Recommendation text
1. REQUIRE REPLACEMENT OF THE MICROSWITCH ON A PERIODIC BASIS IN ALL CIRCUITRY THAT CONTROLS THE OPERATION OF THE FAN ASSEMBLY. 2. CONDUCT A REVIEW OF THE SHOP OVERHAUL MANUALS FOR PROPER INFORMATION ON BALANCING PROCEDURES. DEFINITE TOLERANCES SHOULD BE ESTABLISHED FOR THE DRILLING OF LIGHTENING HOLES, SUCH AS SIZE, NUMBER ALLOWED, SPACING, ETC. 3. REASSESS THE FUNCTIONAL TESTING OF THE OVERSPEED SWITCH ASSEMBLY TO ASSURE PROPER SPEED CUTOUT. 4. REQUIRE A THOROUGH EXAMINATION AS TO CAUSE OF AN OVERSPEED TRIP BEFORE A RESET IS ACCOMPLISHED.
In plain language (FlightFinder summary)
The FAA is directed to mandate regular replacement of specific switches that control fan operation and to verify that maintenance manuals include clear guidelines for balancing components and drilling holes. Additionally, officials must ensure testing procedures confirm that speed-limiting devices function correctly and require a detailed investigation into any speed-related malfunctions before allowing the system to be reset. These steps aim to prevent mechanical failures and ensure reliable safety mechanisms in aircraft fan systems.
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 | Jul 2, 1970 |
| NTSB number | LAX70I0022 |
| Addressees | FAA |
External links
NTSB safety recommendations are advisory; addressees are not legally required to adopt them. Source: NTSB CAROL (public domain).