Commonwealth legislation

AD/BELL 412/22 - Main Transmission Spiral Bevel Gear

In ForceCTH

Jurisdiction

Commonwealth

Collection

legislative instrument

Plain English Summary

3/10 complexity

This airworthiness directive requires operators of Bell 412 helicopters fitted with spiral bevel gear P/N 204-040-701-103 (with that gear under 250 hours total time‑in‑service) to inspect the transmission sump oil filter and the gear teeth for metal contamination, cracks, chipping or deformation, and to replace any defective parts before further flight. Inspections must be repeated at short, prescribed intervals until the gear reaches 250 hours. It responds to a detected metallurgical inclusion that may cause early gear failure; operators pay inspection, downtime and replacement costs, and the regulator sets timing and grounding rules.

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/BELL 412/22 - Main Transmission Spiral Bevel Gear.

AD/BELL 412/22 - Main Transmission Spiral Bevel Gear

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

View image in the official source
Bell Helicopter Textron 412 Series Helicopters

AD/BELL412/22 Main Transmission Spiral Bevel Gear 7/89

Applicability: All 412 series helicopters with main transmission containing spiral bevel gear P/N 204-040-701-103 with less than 250 hours total time in service.

Requirement: 1. Remove and inspect the transmission internal sump oil filter for evidence of metal contamination (eg, steel particles in splinter, granular or flake form). If metal contamination is evident replace worn parts before further flight. Refit oil filter.

Remove a quill pad cover P/N 204-040-174-001 or rotor brake quill from the transmission main ring gear case to allow access to the spiral bevel gear. Inspect all teeth of the gear for evidence of cracks, chipping and deformation. If cracks, chipping or metal deformation is evident replace gear before further flight. Refit component removed for access.

Note: FAA Emergency AD 89-08-05 refers.

Compliance: 1. Within 10 hours time in service or seven days whichever occurs first after 8 May 1989. Thereafter reinspect before the first flight of the day until gear has operated for 250 hours time in service.

Within 10 hours time in service or seven days whichever occurs first after 8 May 1989. Thereafter reinspect at intervals not exceeding 50 hours time in service until gear has operated for 250 hours time in service.

Background: After a pilot reported an occasional unusual noise in flight, inspection of the main transmission revealed two large pieces of gear teeth that had fractured from the spiral bevel gear P/N 204-040-701-103. Metallurgical examination revealed the presence of a low alloy metallic inclusion which occurred during processing of the gear material. This inclusion may result in failure of the gear within the first 250 hours time in service.

Source text

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

1 AD/BELL 412/22 - Main Transmission Spiral Bevel Gear

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

Bell Helicopter Textron 412 Series Helicopters

AD/BELL412/22 Main Transmission Spiral Bevel Gear 7/89

Applicability: All 412 series helicopters with main transmission containing spiral bevel gear P/N 204-040-701-103 with less than 250 hours total time in service.

Remove a quill pad cover P/N 204-040-174-001 or rotor brake quill from the transmission main ring gear case to allow access to the spiral bevel gear. Inspect all teeth of the gear for evidence of cracks, chipping and deformation. If cracks, chipping or metal deformation is evident replace gear before further flight. Refit component removed for access.

Note: FAA Emergency AD 89-08-05 refers.

Within 10 hours time in service or seven days whichever occurs first after 8 May 1989. Thereafter reinspect at intervals not exceeding 50 hours time in service until gear has operated for 250 hours time in service.