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Airworthiness Directive 04-2585

recurring
AD 04-2585 · 2004-02-09 · airframe

Airworthiness Directives; Learjet Model 31, 31A, 35, 35A (C-21A), 36, and 36A Airplanes

What this AD requires

This amendment adopts a new airworthiness directive (AD), applicable to certain Learjet Model 31, 31A, 35, 35A (C-21A), 36, and 36A airplanes, that requires modification of the drag angles of the fuselage and engine pylons to gain access to the shear webs of the forward engine beams; repetitive inspections of the shear webs of the forward engine beams for cracks; follow-on actions; and modification/ repair of the shear webs of the forward engine beams, as necessary, which terminates the repetitive inspections. This action is necessary to prevent significant structural damage to the engine pylons, possible separation of the engines from the fuselage, and consequent reduced controllability of the airplane. This action is intended to address the identified unsafe condition.

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 04-2585 applies to

MakesLearjet
Models31A, 35, 35A, 36, 36A

certain

Whether AD 04-2585 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 04-2585 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.