AD/GBK 117/4 - Landing Gear Electrical Bonding

The directive directly affects the owners and operators of MBB-BK 117 aircraft bearing serial numbers 7001 through 7261 inclusive. Because the compliance obligation is measured in hours time in service, it also affects any person or organisation responsible for maintaining or operating these aircraft after 12 December 1991, including maintenance organisations and pilots in command who must ensure the aircraft remains within the compliance window. The related retrieval context from the Air Navigation Act 1920, section 16, extends the practical reach of the directive to the owner, the operator, the hirer, the pilot in command and any other pilot of an aircraft that arrives in or departs from Australian territory on an international flight. Under that provision, compliance with applicable Commonwealth laws, including this directive, is made a condition of any licence, permission or approval granted under the Air Navigation Act or its regulations.

The Civil Aviation Act 1988, section 4A, further connects the directive to aircraft registered in a Contracting State where an 83 bis agreement has transferred registry functions to Australia. In such cases, provisions of the Civil Aviation Act and regulations, including airworthiness directives issued under Part 39, apply to the aircraft as if it were an Australian aircraft, provided the agreement states that the applied provision relates to the transferred function. Consequently, the directive may affect foreign-registered BK 117 aircraft operating under such agreements when the relevant function includes airworthiness requirements.

The primary duty created by the instrument is the obligation to perform the landing gear electrical bonding action in accordance with MBB Alert SB 117-90-104 within 50 hours time in service after 12 December 1991 for every aircraft falling within the stated serial number range. This duty rests on the owner and operator of each affected aircraft. The directive does not confer any express rights on affected persons. It contains no provision for exemptions, extensions or alternative compliance methods, nor does it establish any right to operate the aircraft without completing the required action.

The related retrieval context from Air Navigation Act 1920, section 16, imposes a parallel duty on the owner, operator, hirer, pilot in command and any other pilot to comply with all applicable Commonwealth laws when the aircraft is engaged in international flights to or from Australian territory. Non-observance of the directive would therefore constitute a breach of that statutory condition. Section 4A of the Civil Aviation Act 1988 similarly requires that the provisions of the Act and regulations, including this directive, be treated as applying to aircraft subject to qualifying 83 bis agreements, thereby extending the duty to comply to those aircraft when Australia has assumed the relevant registry functions.

The source text of the directive itself does not specify any penalties or enforcement mechanisms. It simply states the applicability, requirement and compliance period. Enforcement of the directive therefore occurs through the general provisions of the Civil Aviation Act 1988 and the Civil Aviation Regulations 1998 that govern airworthiness directives issued under Part 39. The related retrieval context indicates that, under Air Navigation Act 1920, section 16, compliance with the directive is a condition of any licence, permission or approval for international operations. Breach of that condition may affect the validity of such authorisations.

Under Civil Aviation Act 1988, section 4A, failure to apply the directive to an aircraft subject to an 83 bis agreement would mean the aircraft is not treated as compliant with Australian requirements where the agreement transfers the relevant function. The source text provides no further detail on administrative sanctions, suspension of certificates or criminal penalties that may attach to non-compliance.

The directive interacts with the broader framework of the Civil Aviation Act 1988 and the Air Navigation Act 1920 as set out in the related retrieval context. Air Navigation Act 1920, section 16, makes compliance with the directive a condition of any licence, permission or approval for an aircraft arriving in or departing from Australian territory on an international flight. The owner, operator, hirer, pilot in command and any other pilot must therefore ensure the landing gear bonding action has been completed before undertaking such flights, or the aircraft will be operating in breach of that statutory condition.

Civil Aviation Act 1988, section 4A, provides that where an 83 bis agreement transfers a function of the State of registry to Australia, and the agreement states that a provision of the Act or regulations relates to that function, the provision applies to the foreign-registered aircraft as if it were an Australian aircraft. Because the directive is issued under Part 39 of the Civil Aviation Regulations 1998, it constitutes such a provision when the transferred function includes airworthiness requirements. The directive therefore applies to aircraft subject to qualifying 83 bis agreements even though those aircraft are not registered in Australia.

The directive does not override or amend the provisions of the Civil Aviation Act or the Air Navigation Act. Instead, it operates as a specific application of the airworthiness regime established by those Acts and the regulations made under them. No other interactions are described in the source text.

The source text presents the directive as originally issued with the compliance date of 12 December 1991 and the identifier 12/91. No information on any subsequent amendment, revision or cancellation of AD/GBK 117/4 appears in the provided instrument. The applicability range, the requirement to follow MBB Alert SB 117-90-104 and the 50-hour compliance period remain as stated in the original text. The background paragraph concerning inadequate landing gear bonding is likewise unchanged in the source material.

Because the instrument contains no amendment history or revision notes, any later modifications to the directive, if they exist, are not recorded here. The directive continues to operate on the basis of the manufacturer's determination, recorded in the background, that the original bonding was inadequate for electrostatic charge elimination.

The source text of the directive contains no reference to any court challenges, litigation or controversies concerning AD/GBK 117/4. No cases are named in the instrument or in the related retrieval context. The directive is presented solely as a technical airworthiness requirement with a fixed compliance deadline and no indication of legal disputes arising from its issuance or application.

Operators must first confirm that the aircraft serial number falls strictly within the closed range 7001 through 7261 inclusive, as the directive does not apply to aircraft outside this range. The compliance clock runs from the fixed date of 12 December 1991 and is measured in hours time in service, so any aircraft that has accumulated 50 or more hours since that date without the required action will already be non-compliant. The technical content of the required action is not reproduced in the directive but is incorporated by reference to MBB Alert SB 117-90-104, meaning the precise steps, parts and acceptance criteria must be obtained from that bulletin.

The directive does not provide for any extension of the compliance period or for alternative means of compliance. Aircraft engaged in international operations must also satisfy the condition imposed by Air Navigation Act 1920, section 16, which requires compliance with all applicable Commonwealth laws before departure from or arrival in Australian territory. For aircraft subject to 83 bis agreements under Civil Aviation Act 1988, section 4A, the directive applies as if the aircraft were Australian-registered when the agreement transfers the relevant airworthiness function.

To comply with the directive, the owner or operator of each MBB-BK 117 aircraft with a serial number between 7001 and 7261 inclusive must ensure that the landing gear electrical bonding action specified in MBB Alert SB 117-90-104 is completed within 50 hours time in service after 12 December 1991. The work must be performed in accordance with the procedures, materials and standards set out in that service bulletin. Records of the work performed, including the date and the hours time in service at completion, should be retained in the aircraft maintenance documentation to demonstrate compliance.

For aircraft that remain in service after the compliance date, operators should verify the serial number against the applicability statement before each flight and confirm that the required action has been recorded. When planning international flights, the condition in Air Navigation Act 1920, section 16, requires that the directive has been satisfied, as non-compliance would breach the statutory condition attached to any relevant licence or approval. Where an 83 bis agreement applies under Civil Aviation Act 1988, section 4A, the same compliance steps must be followed because the directive applies to the aircraft as if it were an Australian aircraft. No further steps are prescribed in the source text of the directive itself.