Is AD 48-50-01 a recurring Airworthiness Directive?

No — AD 48-50-01 is a one-time directive. Verify it was complied with in the aircraft's records.

Which aircraft does AD 48-50-01 apply to?

AD 48-50-01 applies to Franklin — models 6A4-150-B3, 6A4-150-B31, 6A4-150. Serial/part conditions may narrow it to specific aircraft.

Airworthiness Directive 48-50-01

one-time

AD 48-50-01 · 1948-01-01 · reciprocating engine

Airworthiness Directives; required after each 25 hours of operation. To prevent possible cylinder base flange failure, visual inspection for cracks just abo

Which aircraft AD 48-50-01 applies to

MakesFranklin

Models6A4-150-B3, 6A4-150-B31, 6A4-150

Visually inspect cylinder base flange for cracks every 25 hours of operation on early-type cylinders until replaced by later cylinders.

Whether AD 48-50-01 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 48-50-01 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 →

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.