Is AD 04-21050 a recurring Airworthiness Directive?

No — AD 04-21050 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 04-21050 apply to?

AD 04-21050 applies to Empresa Brasileira De Aeronautica S.A. (Embraer) — models EMB-145. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 04-21050

one-time

AD 04-21050 · 2004-09-22 · airframe

Airworthiness Directives; Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model EMB-135 and EMB-145 Series Airplanes

What this AD requires

This amendment supersedes an existing airworthiness directive (AD), applicable to certain EMBRAER Model EMB-135 and EMB-145 series airplanes, that currently requires revising the airplane flight manual and eventual disconnection of the precooler differential pressure switches. This amendment expands the applicability of the existing AD. This amendment also requires a one-time inspection of those additional airplanes to ensure the disconnection and insulation of the electrical connectors of certain precooler differential pressure switches located in the left and right pylons; and disconnection and insulation of the connectors, if necessary. The actions specified by this AD are intended to prevent incorrect operation of the precooler differential pressure switches, which could result in inappropriate automatic shutoff of the engine bleed valve, and consequent inability to restart a failed engine using cross-bleed from the other engine or possible failure of the anti-ice system. This action is also necessary to ensure that the flightcrew is advised of the procedures necessary to restart an engine in flight using the auxiliary power unit. This action is intended to address the identified unsafe condition.

Which aircraft AD 04-21050 applies to

MakesEmpresa Brasileira De Aeronautica S.A. (Embraer)

ModelsEMB-145

certain

Whether AD 04-21050 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 04-21050 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.