COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Supplementary Equipment
AD/SUPP/13
Amdt 1
Air Equipment Hoists - Earth Bonding 1/92
Applicability: Air-Equipment Hoists P/Nos 76370. All variants, up to and including Serial Numbers 493.
Requirement: 1. Measure the motor current limit resistors P/N 709967 with a milliohmmeter - Maximum permissible value is 0.040 OHM for the two resistors in series.
Note: These can be measured on 76370-30 models using the shunt terminals on the hoist control box.
2. Measure the resistor terminals to ground (the resistor mounting plate) with a megohmmeter - Minimum resistance should be 20 Meg OHM.
3. Install bonding cables and carry out a bonding check in accordance with the Lucas Air Equipment Service Bulletin 25-62-0L.
Note 1: Hoists which have already had bonding jumpers installed in accordance with the original issue 1 of this AD are still required to comply with the requirements of Lucas Air Equipment SB 25-62-0L.
Note 2: Bonding resistance checks are to be carried out with a milliohmmeter capable of resolving to 0.002 OHM.
Note 3: Carry out all checks with main connectors disconnected.
Note 4: Compliance with Lucas Air Equipment SB 25-62-0L is considered Mandatory, French DGAC AD 91-125 refers.
4. Examine all relevant documents to identify any hoists which have exhibited a history of slow operation. All hoists which have exhibited a history of slow operation or have blown circuit breakers in operation shall be returned to an approved overhaul facility for internal inspection.
Compliance: 1. For Requirements 1 and 2. In accordance with the original issue of this AD, ie. prior to hoist operations with cable cutter squib installed, after 9 January 1991.
2. For Requirement 3. For installed hoists; prior to 12 March 1992. For uninstalled hoists; prior to installation in an aircraft.
3. For Requirement 4. In accordance with the original issue of this AD, ie. prior to further hoist operations.
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Background: An electrical failure introducing ground currents in the hoist body may cause an uncommanded cable cut.
In the absence of any advice from the hoist manufacturer of the French DGAC, the original issue of this AD was raised to address the problem.
Both the hoist manufacturer and DGAC have now issued instructions to improve and check the electrical bonding of the hoist installation, and Amendment 1 to this AD has been issued to reflect these instructions.
In addition, Aerospatiale have issued Mandatory Service Bulletins applicable to hoists installed in particular Aerospatiale helicopters. DGAC have also issued Airworthiness Directives mandating compliance with the Aerospatiale SBs. Details and cross reference to corresponding Australian ADs is as follows:
Aircraft | Manufacturers SB | DGAC AD | AUSTRALIAN AD |
AS 350 | 35-42 | 91-165-058(B) | AD/ECUREUIL/47 |
AS 355 | 25-30 | 91-164-042(B) | AD/AS 355/39 |
SA 341 | 25-05 | 91-203-035(B) | AD/GAZELLE/16 |
Overview
The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority (CASA), were enacted to ensure the safe operation of civil aviation within Australia. A notable aspect of these regulations is Part 39, which includes the Schedule of Airworthiness Directives (ADs) aimed at addressing specific safety issues that may arise in aircraft operations. One such AD, AD/SUPP/13 Amendment 1, pertains to air equipment hoists and their earth bonding. This directive was introduced to mitigate the risk of electrical failures that could lead to uncommanded cable cuts due to ground currents in the hoist body. The policy objective is to ensure that the air equipment hoists meet the specified electrical bonding standards to prevent such failures, thereby enhancing the safety of aircraft operations.
Amendment 1 to AD/SUPP/13 was issued following instructions from the hoist manufacturer and the French DGAC to improve and verify the electrical bonding of hoist installations. This legislative instrument mandates specific checks and procedures, including measuring motor current limit resistors, ensuring adequate resistance to ground, and installing bonding cables in accordance with service bulletins. Hoists with a history of slow operation or blown circuit breakers must be inspected at approved overhaul facilities. The compliance dates for these requirements are set to ensure timely implementation and adherence to the safety standards, reflecting CASA's commitment to maintaining high safety benchmarks in civil aviation.
Scope and Application
The Civil Aviation Regulations 1998, specifically Part 39, Schedule of Airworthiness Directives, governs the safety standards for supplementary equipment in aircraft, including air equipment hoists. This regulation applies to all air equipment hoists with part numbers 76370, all variants, up to and including serial numbers 493. The directive mandates compliance with specific technical requirements aimed at ensuring the electrical safety and functionality of these hoists. These requirements include measuring the motor current limit resistors to ensure they do not exceed 0.040 OHM, checking the resistance between the resistor terminals and ground to ensure it is at least 20 Meg OHM, installing bonding cables as per the Lucas Air Equipment Service Bulletin 25-62-0L, and returning hoists with a history of slow operation or blown circuit breakers to an approved overhaul facility for inspection. The compliance dates vary depending on the requirement, with some needing to be met before hoist operations with a cable cutter squib installed, others before a specific date, and some before further hoist operations. The regulation extends to ensuring that any relevant documents are examined to identify hoists that need to be returned for inspection due to operational issues.
Key Provisions
The Civil Aviation Regulations 1998, specifically under Part 39 - 107 Civil Aviation Safety Authority Schedule of Airworthiness Directives, outlines the requirements for air equipment hoists, particularly focusing on earth bonding. This directive applies to Air Equipment Hoists with part numbers 76370, up to and including serial numbers 493 (section 1). The primary requirement is to measure motor current limit resistors, ensuring they do not exceed 0.040 ohms when measured in series (section 1.1). Additionally, it mandates a minimum resistance of 20 megohms between the resistor terminals and the ground, measured using a megohmmeter (section 1.2). The directive also requires the installation of bonding cables and a bonding check in line with Lucas Air Equipment Service Bulletin 25-62-0L (section 1.3).
The obligations under this Act include ensuring that these checks are performed before hoist operations with the cable cutter squib installed, following the original issue date of 9 January 1991 for requirements 1 and 2, and before 12 March 1992 for installed hoists or before installation in an aircraft for uninstalled hoists for requirement 3 (section Compliance 1, 2). Moreover, hoists with a history of slow operation or those that have blown circuit breakers need to be returned to an approved overhaul facility for internal inspection (section Compliance 4).
Failure to comply with these directives may result in significant safety risks, including electrical failures that could lead to uncommanded cable cuts. Although the Act does not explicitly outline penalties, non-compliance could result in severe consequences, such as grounding of the aircraft, until the issues are rectified. The importance of adhering to these requirements is underscored by the cross-referencing with international directives and service bulletins, indicating a global consensus on the necessity for stringent electrical bonding standards to ensure safe operations (section Background).