Revision 1 of an FAA Special Airworthiness Information Bulletin (SAIB) is issued to include all Enstrom piston aircraft. These aircraft use the same fuel system. This SAIB alerts owners and operators of Enstrom Helicopter Corporation manufactured F-28A, F-28C, F-28F, 280, 280C, 280F and 280FX helicopters of a false fuel quantity indication with subsequent risk exposure to fuel exhaustion during flight.

Background
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.

Recommendations
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 applicable maintenance manual to correct any noncompliance. In addition, during Periodic Inspection a visual check of the “wristlock” is recommended to ensure the plastic covers over the “wristlock” connections are tie-wrapped in accordance with the maintenance manual.

References
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.

For Further Information Contact
Ed Cuevas, Aviation Safety Engineer, FAA Safety Management Group, ASW-112, 2601 Meacham Blvd., Fort Worth, Texas, 76137; phone: 817-222-5355; e-mail: ed.cuevas@faa.gov.