Overview

The Airworthiness Directive AD/PW100/11 was issued by the Civil Aviation Safety Authority (CASA) on 22 August 2002 and became effective on 3 October 2002. This directive was introduced to address the unsafe condition of Pratt and Whitney Canada (P&WC) PW100 Series turbine engines fitted with Honeywell Mechanical Fuel Control Units (MFCU) that had not been modified in accordance with P&WC Service Bulletin 21562. The primary concern was the malfunction of a bypass valve diaphragm within the MFCU, which had resulted in loss of throttle response and over-speed conditions, leading to in-flight shutdowns. The directive mandates specific inspection and modification actions to ensure the airworthiness of these engines. The policy objective is to mitigate the identified safety risks and ensure continued safe operation of the affected aircraft.

Scope and Application

The Airworthiness Directive (AD) issued under subregulation 39.1 (1) of the Civil Aviation Regulations 1998 applies specifically to Pratt and Whitney Canada (P&WC) PW100 Series turbine engines equipped with Honeywell Mechanical Fuel Control Units (MFCU) that have not been modified per P&WC Service Bulletin (SB) 21562. This directive mandates a series of inspections and modifications to address a malfunction in the bypass valve diaphragm of the MFCU that has resulted in loss of throttle response, over-speed conditions, and inflight shutdowns. The directive is applicable across the Commonwealth of Australia and requires adherence to the inspection and modification protocols outlined in P&WC SB 21669 and SB 21562, Rev 2 or later. The initial inspection must be carried out within 400 flight hours or at the next aircraft “A” check, whichever occurs later, following the effective date of the directive. Subsequent inspections are required at intervals not exceeding 1200 flight hours or aircraft “3A” check, with a final modification or replacement of the MFCU within 4500 flight hours or 24 months from the effective date of the directive. The AD becomes effective on 3 October 2002, and compliance is monitored by the Civil Aviation Safety Authority (CASA).

Key Provisions

This Airworthiness Directive (AD) issued under subregulation 39.1(1) of the Civil Aviation Regulations 1998 (CAR 1998) pertains to all Pratt and Whitney Canada (P&WC) PW100 series turbine engines equipped with a Honeywell Mechanical Fuel Control Unit (MFCU) that have not been modified according to P&WC Service Bulletin 21562 ((1)). The AD is specifically designed to address safety concerns related to the malfunction of a bypass valve diaphragm in the MFCU, which has led to loss of throttle response, over-speed conditions, and in-flight shutdowns ((2)). The main requirement of the AD is to inspect the MFCU in accordance with P&WC Service Bulletin 21669 ((3)). The initial inspection must be carried out within 400 flight hours or at the next aircraft "A" check, whichever occurs later, following the effective date of the AD ((4)). If the MFCU does not meet the inspection criteria, it must be replaced with a serviceable unit before the next flight ((5)). The second requirement mandates a repeat inspection at intervals not exceeding 1200 flight hours or the next aircraft "3A" check, again whichever occurs later, after the initial inspection ((6)). If the MFCU still does not meet the criteria, it must again be replaced before the next flight ((7)). The final requirement is to replace the MFCU with a unit modified according to P&WC Service Bulletin 21562, Revision 2 or later, within 4500 flight hours or 24 months after the effective date of the AD, whichever comes first ((8)). This replacement constitutes the terminating action for the repetitive inspections required under the second requirement ((9)). The AD imposes obligations on the operators and owners of aircraft equipped with the specified engines and MFCUs to ensure compliance with the inspection and replacement requirements. Operators must conduct the initial and subsequent inspections within the specified time frames and replace the MFCU if it fails to meet the inspection criteria ((10)). Furthermore, they must ensure that the final replacement of the MFCU is completed within the stipulated time frame to terminate the need for further inspections ((11)). Failure to comply with the AD could result in the aircraft being deemed unairworthy, which could lead to severe consequences, including grounding of the aircraft and potential civil or criminal penalties under the Civil Aviation Act 1988 (Cth) and associated regulations ((12)).