Commonwealth legislation

AD/DHC-1/37 - Engine Start Isolation Switch

In ForceCTH

Jurisdiction

Commonwealth

Collection

legislative instrument

Plain English Summary

2/10 complexity

This airworthiness directive requires owners/operators of De Havilland DHC‑1 (Chipmunk) aeroplanes fitted with Mod H85 or similar electric‑start installations to install an engine‑start isolation switch following British Aerospace TNS CT (C1) No. 201 Issue 1 (Requirement). Compliance is mandatory before 19 June 1998 (Compliance). Purpose: to prevent uncommanded propeller rotation if ground power is applied while a starter‑switch fault or inadvertent operation renders the start system live (Background). The installation cost and work fall to the aircraft owner/operator; the regulator prescribes the technical standard (Note).

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/DHC-1/37 - Engine Start Isolation Switch.

AD/DHC-1/37 - Engine Start Isolation Switch

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

View image in the official source
De Havilland DHC-1 (Chipmunk) Series Aeroplanes

AD/DHC-1/37 Engine Start Isolation Switch 7/97

Applicability: All DHC-1 Chipmunk Aircraft fitted with Mod H85 or similar Electric Start installation.

Requirement: Unless previously incorporated, install an isolation switch in accordance with British Aerospace Aerostructures Ltd Technical News Sheet (TNS) CT (C1) No. 201 Issue 1, dated 1 March 1997.

Note: This TNS is classified Mandatory by UK CAA.

Compliance: Prior to 19 June 1998.

This Airworthiness Directive becomes effective on 19 June 1997.

Background: The manufacturer has determined that there is a possibility that a safety hazard could arise with ground power applied to the aeroplane. With the aeroplane electrically safe, an undetected fault in the starter switch, or inadvertent operation of the starter switch could render the engine start system live. The subsequent connection to ground power would cause an uncommanded rotation of the propeller and possibly endanger maintenance personnel.

Source text

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

1 AD/DHC-1/37 - Engine Start Isolation Switch