Commonwealth legislation

AD/DC4/1 - Vacuum System - Modification

In ForceCTH

Jurisdiction

Commonwealth

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legislative instrument

Plain English Summary

6/10 complexity

Requires all Douglas DC‑4 operators to rework the aeroplane vacuum system by either fitting a Genesco No. 40081 oil separator (with a pressure‑relief valve and serviceable for cleaning) or installing a fusible plug in the vacuum‑pump discharge. Compliance requires operators to bear the cost of parts and labour for the modification. The measure is intended to reduce risks from pump overpressure, overheat, or oil ejection by adding relief and fusible‑link protection.

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AD/DC4/1 - Vacuum System - Modification

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Douglas DC4 Series Aeroplanes

AD/DC4/1 Vacuum System - Modification NK

Applicability: All models.

Requirement: Rework the vacuum system in accordance with either of the following modifications:

Replace the present oil separator with a Genesco No. 40081 separator.

The new separator incorporates a pressure relief valve and can be dismantled for cleaning; or

2. Install a fusible plug in the side of the vacuum pump discharge port at right angles to the axis of the discharge port boss.

Note: Some pumps incorporate a plugged hole in the discharge port which may be enlarged to a 3/8 in. NPT tapped hole to accommodate the fusible plug. This plug should employ an AN-840-8D fitting with a binary eutectic mixture of 68 per cent tin and 32 per cent cadmium which has a melting point of 351oF (See Figure 1). The 3/8 in. fusible plug is intended for pumps model 3P211 and 3P485. For smaller pumps a modified AN-840-6D fitting should be used.

or FAA AD 49-46-1; or ANO 105.1.16.0.1.1.

Source text

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

1 AD/DC4/1 - Vacuum System - Modification