Commonwealth legislation

AD/HU 269/69 - Alternator Circuit Protection - Modification

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This Act has been repealed and is no longer in force. It is retained for historical reference.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

2/10 complexity

What it is: A mandatory safety instruction (Airworthiness Directive) requiring electrical system upgrades for specific helicopters to prevent cockpit fires and total power loss.

Who it affects: Owners and operators of Schweizer (Hughes) 269 series helicopters that fly at night or under Instrument Flight Rules (IFR)—meaning when pilots rely on instruments rather than visual cues.

What you must do: Install two circuit protection devices (fuses or circuit breakers):

A 5-amp device on the alternator field wire, labeled "Alternator Field"
A correctly sized device on the main alternator power cable, labeled "Alternator"—the size must match the cable protection standards in aviation regulation ANO 108.32

Why it matters: This prevents dangerous cockpit smoke caused by electrical faults and stops complete electrical failures that could be catastrophic during night flights.

Deadline: Within 100 flight hours after 30 June 1980.

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AD/HU 269/69 - Alternator Circuit Protection - Modification

COMMONWEALTH OF AUSTRALIA CIVIL AVIATION ORDERS CIVIL AVIATION SAFETY AUTHORITY PART 105 SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Schweizer (Hughes) 269 Series Helicopters

AD/HU 269/69 Alternator Circuit Protection - Modification 6/80

Applicability: All 269 Series operating under Instrument Flight Rules (IFR) or Flights at Night in VMC.

Requirement: 1. Install a 5 ampere circuit protective device between the cable-coded P34A20 and the alternator switch (269A4613) and identify as “Alternator Field”.

Note: An inline fuse is an acceptable means of compliance.

Install a circuit protective device between the Alternator positive-cable and the bus. This protective device shall be of a value that will protect the particular sized cable installed and shall be identified as “Alternator”.

Note: A circuit protective device which meets the requirements of the cable and circuit protector coordination chart in ANO 108.32, Appendix 3, Table 6 will be an acceptable means of compliance.

Compliance: Within 100 hours time in service after 30 June 1980.

Background: A recent defect report highlighted the problem of smoke in the cockpit when the field circuit was grounded within the alternator. The above modification should prevent this type of defect and/or an earth on the alternator positive line which necessitates removal of all electrical power from the aircraft. This is a potential hazard in NVMC aircraft. Modification is also considered highly desirable for VFR aircraft.

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Source text

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

1 AD/HU 269/69 - Alternator Circuit Protection - Modification