Is AD 2006-07-21 a recurring Airworthiness Directive?

Yes — AD 2006-07-21 requires a repetitive inspection every 18 months. Next-due depends on the aircraft's time in service.

Which aircraft does AD 2006-07-21 apply to?

AD 2006-07-21 applies to Boeing — models 757-200, 757-200PF, 757. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 2006-07-21

recurring

Official AD 2006-07-21 · FR doc 06-3381 · 2006-04-11 · airframe

Airworthiness Directives; Boeing Model 757 Airplanes Powered by Pratt & Whitney Engines

What this AD requires

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 757 airplanes. This AD requires repetitive inspections for corrosion and cracking of the midspar fittings in the nacelle struts, and corrective actions if necessary. This AD also provides an optional terminating action for the repetitive inspections. This AD results from reports of corrosion and cracking on midspar fittings on the nacelle struts of several Boeing Model 757 airplanes. We are issuing this AD to detect and correct cracking in the midspar fittings of the nacelle struts, consequent reduced structural integrity of the struts, and possible separation of an engine and strut from the airplane.

Repetitive inspection. Re-inspect every 18 months. The next-due date/hours depend on this aircraft’s time in service — a records report computes it from the logbooks.

Which aircraft AD 2006-07-21 applies to

MakesBoeing

Models757-200, 757-200PF, 757

Serial-conditional — narrows to serials 1–639.

Applies to airplanes having line numbers 1 through 639 inclusive (represented here as the serial range), certificated in any category, and powered by Pratt & Whitney engines.

Whether AD 2006-07-21 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 2006-07-21 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.