Is AD 99-50 a recurring Airworthiness Directive?

No — AD 99-50 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 99-50 apply to?

AD 99-50 applies to Airbus — models A320, A321. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 99-50

one-time

AD 99-50 · 1999-01-08 · airframe

Airworthiness Directives; Airbus Model A319, A320, and A321 Series Airplanes

What this AD requires

This amendment adopts a new airworthiness directive (AD), applicable to certain Airbus Model A319, A320, and A321 series airplanes, that requires modification of the airplane wiring to separate the electrical inputs sent by the engine interface units (EIU) to certain probe heat computers (PHC). This amendment is prompted by the issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent simultaneous loss of heating to pitot probes 1 and 3, which could result in incorrect airspeed indications to both the pilot's and first officer's airspeed indication systems. Malfunction of these systems could result in reduced controllability of the airplane.

Which aircraft AD 99-50 applies to

MakesAirbus

ModelsA320, A321

certain

Whether AD 99-50 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 99-50 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.