Commonwealth legislation

AD/PHOF/1 - Blade Pitch Change Fork - Replacement

In ForceCTH

Jurisdiction

Commonwealth

Collection

legislative instrument

Plain English Summary

3/10 complexity

This airworthiness directive requires replacing the blade pitch change forks and associated pitch-change blocks on Hoffman HO‑V123 variable‑pitch propellers fitted to Lycoming O‑540 and IO‑540 engines, and marking modified propellers “SB 3”. An appropriately approved overhaul organisation must perform the change per overhaul manual E 105. The manufacturer reports cracked forks; the rule is intended to reduce failure risk. Aircraft owners/operators pay for the work and must meet staged compliance dates, with aerobatic‑certificated aircraft required to comply sooner.

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/PHOF/1 - Blade Pitch Change Fork - Replacement.

AD/PHOF/1 - Blade Pitch Change Fork - Replacement

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

View image in the official source
Propellers - Variable Pitch - Hoffman

AD/PHOF/1 Blade Pitch Change Fork - Replacement 5/83

Applicability: All Hoffman variable pitch Model HO-V123 series propellers fitted to Lycoming Model 0-540 and IO-540 series engines.

Requirement: Required action:

(a) The forks and the pitch change blocks are to be exchanged in accordance with instructions given in overhaul manual E 105 by an appropriately approved organisation.

Part	Old P/No.	New P/No.
Pitch change fork	VP 20-747	VP 20-909
Pitch change block, symetric alternatively	VP 20-554	VP 20-912
Pitch change block, unsymmetrical	VP-20-550	VP 20-908

(b) Mark modified propellers with 4 mm high letters "SB 3" above the manufacturing year.

Note: German A.D. Luftfahrt-Bundesamt 63-303-61-83-29 refers.

Compliance: Part 1: All models fitted to aerobatic certificated aircraft, by 31st July, 1983.

Part 2: All other models by the next reconditioning inspection or 30th November, 1983 whichever is the sooner.

Background: The manufacturer advises that reports have been received of cracked pitch change forks particularly on aerobatic certificated aircraft, consequently a stronger designed pitch change fork has been introduced.

Source text

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

1 AD/PHOF/1 - Blade Pitch Change Fork - Replacement