A-93-171
NTSB Safety Recommendation — Aviation
Recommendation text
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: CONDUCT AN ENGINEERING DESIGN REVIEW OF FRISE AILERON CONTROL SYSTEMS INSTALLED IN TWIN COMMANDER 690 SERIES AIRPLANES TO ASCERTAIN THE ADEQUACY OF LATERAL CONTROL WHEEL FORCE GRADIENTS, PARTICULARLY AS THEY MIGHT BE AFFECTED BY IMPROPER AILERON SYNCHRONIZATION, RIGGING, CABLE TENSION, OR FREE-PLAY OF THE AILERON TRIM TAB. OTHER RELATED PARAMETERS THAT SHOULD BE CONSIDERED INCLUDE THE FOLLOWING: EFFECTS/LIMITATIONS (ON SYNCHRONIZATION AND HINGE MOMENTS) OF THE RIGHT AILERON GROUND ADJUSTABLE TRIM TAB, VARIABLE CABLE TENSION DUE TO TEMPERATURE EFFECT, PARTICULARLY AT COLD TEMPERATURES AND/OR HIGH ALTITUDE; AEROELSTIC EFFECTS AT HIGH SPEED; AND DEFORMATION OF WING-AILERON STRUCTURE AND AILERON HINGES IN TURBULENCE OR A HIGH SPEED OR LOAD FACTOR. AN AIRWORTHINESS DIRECTIVE SHOULD BE ISSUED TO CORRECT ANY DEFICIENCIES NOTED, AND IF APPROPRIATE, THE MANUFACTURER SHOULD BE REQUIRED TO INCLUDE NEW OR AMENDED AILERON CONTROL SYSTEM RIGGING AND SYNCHRONIZATION PROCEDURES IN THE RESPECTIVE MAINTENANCE MANUALS.
In plain language (FlightFinder summary)
The Federal Aviation Administration is asked to conduct an engineering design review of Frise aileron control systems in Twin Commander 690 series airplanes, focusing on lateral control wheel force gradients and potential effects from improper synchronization, rigging, cable tension, or aileron trim tab free-play. The review should also consider the right aileron ground adjustable trim tab, temperature effects on cable tension, aeroelastic effects at high speed, and structural deformation under turbulence or high load factor. An airworthiness directive should be issued if deficiencies are found, and the manufacturer may need to update maintenance manuals with revised rigging and synchronization procedures.
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 | May 25, 1995 |
| NTSB number | LAX93FA333 |
| Addressees | FAA |
External links
NTSB safety recommendations are advisory; addressees are not legally required to adopt them. Source: NTSB CAROL (public domain).