Is AD 98-21-09 a recurring Airworthiness Directive?

No — AD 98-21-09 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 98-21-09 apply to?

AD 98-21-09 applies to Robinson — models R22. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 98-21-09

one-time

Official AD 98-21-09 · FR doc 98-31328 · 1998-11-24 · airframe

Airworthiness Directives; Robinson Helicopter Company Model R22 Helicopters

What this AD requires

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 98-21-09, which was sent previously to all known U.S. owners and operators of Robinson Helicopter Company (RHC) Model R22 helicopters by individual letters. This AD requires installing fuel tank vent tube(s), with modified attachment to the mast tube, if not previously accomplished; installing a spring into the flexible tube leading to the main fuel tank; and installing a spring into the flexible tube leading to the auxiliary fuel tank, if an auxiliary fuel tank is installed. This amendment is prompted by an incident in which the flexible vent connecting the rigid vent tube to the main fuel tank kinked, resulting in fuel starvation and a hard landing after uncommanded engine shutdown. The actions specified by this AD are intended to prevent fuel starvation, loss of engine power, and a subsequent forced landing.

Which aircraft AD 98-21-09 applies to

MakesRobinson

ModelsR22

Part-conditional — A731-1, A731-2, A731-3, A729-7, A729-17, A695-1, B408-1, B408-2.

Applies to R22 helicopters overhauled by Robinson Helicopter Company prior to January 1, 1991, lacking a main-fuel-tank-only configuration with dual vent tubes, or (if an auxiliary tank is installed) lacking a crossover vent tube between tanks; requires vent tube/spring upgrade per RHC kit KI-140 and SB-83/SB-84.

Whether AD 98-21-09 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 98-21-09 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.