Is AD 2021-08-04 a recurring Airworthiness Directive?

No — AD 2021-08-04 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 2021-08-04 apply to?

AD 2021-08-04 applies to Boeing — models 737-200, 737-300, 737-400, 737-500, 737-600, 737-700, 737-700C, 737-800. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 2021-08-04

one-time

Official AD 2021-08-04 · FR doc 2021-08213 · 2021-04-21 · airframe

Airworthiness Directives; The Boeing Company Airplanes

What this AD requires

The FAA is superseding Airworthiness Directive (AD) 2013-07- 09, which applied to certain The Boeing Company Model 737-700, -700C, - 800, and -900ER series airplanes, Model 747-400F series airplanes, and Model 767-200 and -300 series airplanes. AD 2013-07-09 required a general visual inspection for affected serial numbers of the crew oxygen mask stowage box units, and replacement or re-identification as necessary. This AD retains the requirements of AD 2013-07-09 and expands the applicability. This AD was prompted by a determination that the affected parts may be installed on airplanes outside the original applicability of AD 2013-07-09. The FAA is issuing this AD to address the unsafe condition on these products.

Which aircraft AD 2021-08-04 applies to

MakesBoeing

Models737-200, 737-300, 737-400, 737-500, 737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER, 737-8, 737-9, 747-200B, 747-200C, 747-200F, 747-400, 747-400D, 747-400F, 757-200, 757-200PF, 757-200CB, 757-300, 767-200, 767-300, 767-300F, 767-400ER, 737, 747, 757, 767

Whether AD 2021-08-04 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 2021-08-04 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.