AD/GENERAL/22 - Engine Oil Tank - Modification

Overview

The Civil Aviation Regulations 1998, as amended by AD/GENERAL/22, was enacted to address safety concerns associated with engine oil supply systems in aeroplanes equipped with hydraulically operated feathering propellers. The Australian Civil Aviation Safety Authority (CASA) introduced these regulations to ensure that in the event of an engine oil supply exhaustion, sufficient oil is retained in the tank to feather the propeller. This is critical for maintaining control and safety during flight. The policy objective behind these regulations is to prevent potential hazards such as oil starvation during cold starts or overheating under high power conditions by mandating specific modifications to the engine oil tanks and, where applicable, the hopper necks. These measures are designed to uphold the integrity of the oil supply system and enhance overall aircraft safety.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105 under the Civil Aviation Safety Authority, applies to all aeroplanes fitted with hydraulically operated feathering propellers that draw their feathering oil supply from the engine oil tank. The regulation mandates modifications to the engine oil tanks to ensure that in the event of an engine oil supply exhaustion, sufficient oil remains in the tank to enable the propeller to be feathered. This reserve supply must be exclusively available to the feathering pump. The directive is issued to mitigate risks such as oil starvation under cold starting conditions and overheating of oil under high power, which can occur if the standpipe height in certain oil tank installations is increased. Modifications may also be required to the neck of the hopper in cases where a hopper is present in the oil tank to prevent any restriction of oil flow. This regulation extends to all relevant aircraft within the Commonwealth of Australia, ensuring compliance with civil aviation safety standards. Subordinate instruments may further detail or refine the application of these airworthiness directives, ensuring that all modifications are implemented in a manner that maintains the safety and reliability of aircraft operations. The regulation does not specify any exclusions, exemptions, or thresholds, thereby applying uniformly to all applicable aircraft.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, establish the Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives. The directive AD/GENERAL/22 pertains to all aeroplanes equipped with hydraulically operated feathering propellers that draw their feathering oil supply from the engine oil tank (section 1). This directive requires modifications to the engine oil tanks to ensure that sufficient oil is retained in the tank during engine oil exhaustion. The primary requirement is to rework the engine oil supply standpipe so that, in the event of engine oil depletion, enough oil remains in the tank to feather the propeller. This reserve supply must be exclusively available to the feathering pump (section 1(1)). In installations where the oil tank incorporates a hopper, the height of the standpipe modification could potentially restrict oil flow to the hopper, leading to oil starvation during cold starts and overheating during high-power operations. To mitigate these risks, the directive also requires modifications to the hopper's neck to prevent any restriction of oil flow (section 1(2)). The obligations imposed by AD/GENERAL/22 on the parties governed by this directive include ensuring that all modifications to the engine oil tanks and hoppers are carried out in accordance with the specified requirements. Aircraft operators must verify that the modifications have been completed correctly and that the necessary documentation is maintained. This includes adhering to any referenced Australian National Standards (ANS) or other directives such as ANO 105.1.0.1.49 or AD/DC3/22 (section 1(2)). Operators must also ensure that their aircraft are airworthy and comply with all relevant safety regulations before conducting any flight operations. This involves regular maintenance checks and the implementation of any required modifications as stipulated by CASA to ensure continued compliance with airworthiness standards. Failure to comply with the requirements of AD/GENERAL/22 can lead to serious consequences. Firstly, non-compliance may result in the aircraft being deemed unairworthy, which can lead to grounding of the aircraft until the necessary modifications are completed. Under the Civil Aviation Act 1988, operators who fail to comply with airworthiness directives can face substantial penalties. The maximum penalty for an individual who contravenes these regulations can include fines up to $21,000 and/or imprisonment for up to two years (section 471). For corporations, the penalties can be significantly higher, with fines up to $1,050,000 (section 471). Additionally, CASA has the authority to impose administrative penalties, including suspension or revocation of the aircraft’s certificate of airworthiness, which can have severe operational and financial repercussions for the operator.