Commonwealth legislation

AD/GENERAL/43 - Power Supply Connections to Hourmeters

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This Act has been repealed and is no longer in force. It is retained for historical reference.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 directive requires operators to inspect hourmeter wiring and prevent hourmeters from sharing Class 1 (critical) electrical circuits. If an hourmeter is on a critical circuit, operators must add graded protection (a dedicated fuse/circuit breaker that trips before the main breaker) or rewire it to a separate, non‑critical circuit with its own protection.

Where an hourmeter is powered through the landing‑gear up‑lock switch, a dedicated fuse or breaker sized to fail before the main landing‑gear breaker is mandatory. This affects all aircraft with hourmeters.

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AD/GENERAL/43 - Power Supply Connections to Hourmeters

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Aircraft - General

AD/GENERAL/43 Power Supply Connections to Hourmeters 6/70

Applicability: All aircraft fitted with hourmeters.

Requirement: 1. Inspect the hourmeter installation to ascertain that it is NOT connected to a Class 1 circuit.

If the hour meter is connected to a Class 1 circuit, separate graded protection must be fitted, or the system must be removed from the Class 1 circuit and connected through a separate protective device.

Note: Hourmeters utilizing the power supply through the landing gear up lock switch (i.e. Beech Aircraft) should have fitted, at the up lock switch connection, a fuse or circuit breaker of such a value that it will open the circuit before the landing gear control and indication circuit breaker trips.

Compliance: Within 100 hours time in service after 30 June 1970.

Source text

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

1 AD/GENERAL/43 - Power Supply Connections to Hourmeters