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Airworthiness Directive 97-20-04

recurring
Official AD 97-20-04 · FR doc 97-25059 · 1997-09-22 · airframe

Airworthiness Directives; Enstrom Helicopter Corporation Model F- 28A, F-28C, 280 and 280C Helicopters

What this AD requires

This amendment adopts a new airworthiness directive (AD) that is applicable to Enstrom Helicopter Corporation (Enstrom) Model F-28A, 280 and certain serial-numbered F-28C and 280C helicopters. This action requires an inspection of the voltage control system and an owner/ operator (pilot) cockpit check of the amperage of the electrical system. If certain Prestolite-manufactured components are installed, additional tests and actions are required before further flight and at each pre-flight run-up and annual inspection thereafter. A terminating action is provided by replacing the existing voltage control system with a transistorized system. This amendment is prompted by 14 reports of voltage control system problems, including one incident in which smoke emanated from the radio panel during flight, forcing the pilot to make an emergency landing. The actions specified in this AD are intended to prevent an electrical overload and a failure of the voltage regulator and over-voltage relay, that could result in an inflight fire, and subsequent forced landing of the helicopter.

Repetitive inspection. Re-inspect. The next-due date/hours depend on this aircraft’s time in service — a records report computes it from the logbooks.

Which aircraft AD 97-20-04 applies to

MakesEnstrom Helicopter Corporation
Part-conditional — VSF7203, X16799, X17621, FOC-4002A.

Prestolite voltage regulator P/N VSF7203 and over-voltage relay P/N X16799/X17621/FOC-4002A inspection, adjustment, and/or replacement per Enstrom Service Directive Bulletin No. 0086 (Mar 31, 1996). Specific model not named in extracted text.

Whether AD 97-20-04 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.

How AD compliance is recorded

A valid compliance record (14 CFR 43.9) states:

Method of compliance — The specific action taken (inspected, replaced, modified) and to what revision.
Date — When the work was done.
Aircraft time — Total time in service / tach at compliance — how recurring next-due is computed.
Signature & certificate — The A&P/IA who returned it to service, with certificate number.
Is AD 97-20-04 complied with on your aircraft?

Tailplate reads a tail number’s logbooks and matches every applicable AD — including this one — to its compliance evidence, with recurring next-due dates computed.

Look up a tail number →Read the full directive (Federal Register)

Applicability is derived from the FAA directive corpus and is advisory, not a legal airworthiness determination. Compliance is established only from an aircraft’s actual records.