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Airworthiness Directive 2008-21-04

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Official AD 2008-21-04 · FR doc E8-23643 · 2008-10-09 · airframe

Airworthiness Directives; Hawker Beechcraft Corporation Model 390 Airplanes

What this AD requires

The FAA is adopting a new airworthiness directive (AD) for certain Hawker Beechcraft Corporation Model 390 airplanes. This AD requires you to modify the cabin barometric pressure switch and cabin altitude high switch installations and perform a functional test of the switches and related systems. This AD results from the possibility of barometric pressure switch electrical connections being incorrectly connected or inadvertently disconnected. We are issuing this AD to modify the cabin barometric pressure switch and cabin altitude high switch to prevent them from becoming incorrectly connected or inadvertently disconnected, which may result in no CABIN ALT HI annunciation in the cockpit and no automatic deployment of the cabin oxygen masks. This failure could lead to incapacitation of the crew due to hypoxia with possible inability to control the airplane.

Which aircraft AD 2008-21-04 applies to

Applicability depends on the aircraft’s type certificate — check it against the specific tail.

Whether AD 2008-21-04 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 2008-21-04 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.