Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
January 9, 2012
This is information only. Recommendations
This Special Airworthiness Information Bulletin (SAIB) alerts owners
and operators of Enstrom Helicopter Corporation-manufactured (Enstrom)
280 FX helicopters of a false fuel quantity indication with subsequent
risk exposure to fuel exhaustion during flight. At this time, this
airworthiness concern is not an unsafe condition that would warrant
airworthiness directive (AD) action under Title 14 of the Code of
Federal Regulations (14 CFR) part 39.
There has been a report of a helicopter accident that occurred after
fuel exhaustion. Investigation revealed a false “Full” fuel quantity
indication on the fuel indicator as contributory. This false reading
was due to the fuel level sending unit wires being disconnected. A
false fuel quantity indication of “Full” results when the fuel level
sending unit wires are disconnected at the “wristlock” located between
the tops of the left and right fuel tanks, with the master switch in
the “On” position.
We recommend that prior to each flight the visual check specified in
the flight manual be performed to verify fuel quantity in the fuel
tank. When the fuel tank is “Full” the fuel quantity indicator in the
cockpit should read “Full.” If the fuel quantity in the tank is less
than “Full” and the fuel quantity indicator reads “Full” then the fuel
indicating system should be serviced per the maintenance manual to
correct any noncompliance. Additionally, we recommend a visual check of
the “wristlock” during each Periodic Inspection to ensure the plastic
covers over the “wristlock” connections are tie-wrapped in accordance
with the maintenance manual.
Enstrom Maintenance Manual, page MM-3-7, Section 3-2 Periodic
Inspection, Nature of Inspection B.2(d); pages MM-13-72, 73 and 74,
Section 13-10 Fuel System, B(1)(c) and B(2)(c); and Enstrom Rotorcraft
Flight Manual RFM 28-AC-020, pages 4.3 and 4.4, paragraphs 12 and 23.