Commonwealth legislation

AD/B747/52 - Lower Fuselage Frames

RepealedCTH

This Act has been repealed and is no longer in force. It is retained for historical reference.

Jurisdiction

Commonwealth

Collection

legislative instrument

Plain English Summary

3/10 complexity

This mandatory safety directive requires owners/operators of the first 265 Boeing 747s to inspect lower fuselage frames in the bottom half of the airframe for fatigue cracks, following Boeing's service instructions. Initial and repetitive inspection intervals are set (first before 7,000 landings or within 500 landings after 31 Dec 1986, then every 3,000 landings), with reinforcement per Boeing allowing a 12,000‑landing interval only for the reinforced frames.

Australia’s version keeps extra precautionary inspections after reinforcement to detect new cracks in surrounding metal.

JSON API

Deep dive

Want the full deep dive?

Zoe can write the in-depth analysis on top of the summary above: how it works, who it affects and what each part actually does.

Current sections

Direct links to the current provisions in AD/B747/52 - Lower Fuselage Frames.

AD/B747/52 - Lower Fuselage Frames

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

View image in the official source
Boeing 747 Series Aeroplanes

AD/B747/52 Lower Fuselage Frames 12/86

Applicability: All models, line numbers 1 to 265.

Requirement: Inspect in accordance with Boeing Alert SB 747-53A2237 Revision 1.

Compliance: Before exceeding 7,000 landings or within the next 500 landings after 31 December 1986 whichever occurs later; and thereafter at intervals not exceeding 3,000 landings.

If the strap and angle reinforcement is accomplished in accordance with the ASB, the repeat inspection interval may be extended to 12,000 landings for reinforced frames only.

Background: Numerous reports have been received from overseas of cracked fuselage frames in the lower lobe in Sections 42 and 46. Cracks have been found as early as 6874 landings.

This Directive implements the intent of the FAA AD, with some local variations. One which should be noted is the requirement to carry out precautionary inspections after reinforcement, to cover the possibility of further cracking in fatigue-damaged structure which has not been replaced.

Source text

Sourced from the Federal Register of Legislation (legislation.gov.au), CC BY 4.0.

1 AD/B747/52 - Lower Fuselage Frames