AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.
Fokker F50 (F27 Mk 50) Series Aeroplanes
AD/F50/87 Pitot & Static Port Heating Wiring 8/2004
Applicability: Model F.27 Mk.050, Mk.0502 and Mk.604 aeroplanes, all serial numbers. Requirement: Modify the wiring of the pitot and static port heating in accordance with Section 2 -
Accomplishment Instructions of Fokker Service Bulletin F50-30-028 dated 4 March 2004 or Revision 1 dated 26 April 2004.
Note 1: Fokker Services Manual Change Notification - Maintenance Documentation (MCNM) F50-048 dated 4 March 2004 also pertains to this subject.
Note 2: CAA-NL AD 2004-038 (A) Corr refers.
Compliance: Within the next 36 months after the effective date of this Directive. This Airworthiness Directive becomes effective on 5 August 2004.
Background: The Netherlands CAA has received a report from a Fokker 50 operator of intermittent events where, during autopilot engagement in IAS-Mode decent, the aircraft suddenly pitched nose down resulting in an overspeed situation. Investigation revealed a failed heater element in the left hand upper pitot-static tube, which was not detected by the current sensor, and as a result no “PITOT HEAT” alert was generated. In a single air data computer (ADC) configuration only pressure from the left hand upper pitot head is used. In this instance freezing of the pitot head resulted in erroneous ADC airspeed output
Fokker F50 (F27 Mk 50) Series Aeroplanes
AD/F50/87 (continued)
Currently, to detect failures, each heating element is connected in series with a current sensor, which is designed to detect low or zero heater current. This Directive requires the modification of the heater circuit wiring to extend detection capability to include heating element short circuits to ground and heating element failures that result in a low insulation resistance.
James Coyne
Delegate of the Civil Aviation Safety Authority 23 June 2004
The above AD is notified in the Commonwealth of Australia Gazette on 14 July 2004.
Overview
The Civil Aviation Safety Authority Airworthiness Directive (AD) AD/F50/87, enacted in 2004, was introduced to address the safety concerns associated with the pitot and static port heating wiring in Fokker F50 (F27 Mk 50) Series aeroplanes. This AD was issued under the Civil Aviation Safety Regulations 1998, which were enacted by the Australian Parliament, and it aims to correct an unsafe condition identified in the aircraft's pitot and static port heating wiring that could potentially lead to hazardous flight conditions. The directive requires specific modifications to the wiring to ensure better detection of failures and shorts, enhancing the overall airworthiness of the aircraft. Compliance with this AD is mandatory for all Fokker F50 aeroplanes and must be completed within 36 months of the AD's effective date.
Scope and Application
The Airworthiness Directive (AD) issued under subregulation 39.1 (1) of the Civil Aviation Safety Regulations 1998 pertains specifically to the Fokker F50 (F27 Mk 50) Series Aeroplanes, encompassing all serial numbers of the Model F.27 Mk.050, Mk.0502, and Mk.604 aeroplanes. This directive applies to all aircraft of the specified models operating within the jurisdiction of the Civil Aviation Safety Authority (CASA). The directive mandates the modification of the pitot and static port heating wiring to address an unsafe condition identified through a reported incident involving a Fokker 50 operator. The modification must be carried out in accordance with the instructions set out in Fokker Service Bulletin F50-30-028 dated 4 March 2004 or its Revision 1 dated 26 April 2004, and additionally referenced in Fokker Services Manual Change Notification - Maintenance Documentation (MCNM) F50-048 dated 4 March 2004. Compliance with this directive is required within 36 months from the effective date of 5 August 2004.
Key Provisions
The Airworthiness Directive (AD) F50/87 issued by the Civil Aviation Safety Authority (CASA) pertains to Fokker F50 (F27 Mk 50) Series aeroplanes, specifically models F.27 Mk.050, Mk.0502, and Mk.604, with all serial numbers covered by this directive (AD/F50/87, applicability). The directive requires that the wiring of the pitot and static port heating must be modified to address safety issues identified during autopilot engagement in IAS-Mode descent, where an overspeed situation was caused by the failure of a heater element in the left-hand upper pitot-static tube (AD/F50/87, requirement). This modification is to be carried out in accordance with the instructions provided in Section 2 – Accomplishment Instructions of Fokker Service Bulletin F50-30-028 dated 4 March 2004, or Revision 1 dated 26 April 2004. Additionally, the Fokker Services Manual Change Notification - Maintenance Documentation (MCNM) F50-048 dated 4 March 2004 is relevant to this directive.
The AD mandates that the specified modification must be completed within 36 months from the effective date of the directive, which is 5 August 2004 (AD/F50/87, compliance). The directive responds to a reported incident where the failure of a heater element led to erroneous airspeed readings due to freezing of the pitot head, resulting in a dangerous overspeed situation during autopilot engagement. To mitigate such risks, the directive requires an update to the wiring of the pitot and static port heating systems, extending the detection capability to include short circuits to ground and failures resulting in low insulation resistance.
Entities governed by this AD, such as aircraft operators and maintenance organisations, must ensure that the modifications are completed within the stipulated timeframe. They must adhere to the detailed instructions provided in the Fokker Service Bulletin and update their maintenance documentation accordingly. Failure to comply with the AD may result in the aircraft being considered unairworthy, potentially leading to grounding and regulatory enforcement actions.
Under the Civil Aviation Safety Regulations 1998, non-compliance with an Airworthiness Directive can lead to civil penalties, including fines, and criminal charges for those responsible. The severity of the penalties can depend on the extent of the non-compliance and the impact on aviation safety. For instance, knowingly allowing an aircraft to operate without compliance with an AD could result in significant fines and imprisonment for directors or responsible persons. Additionally, CASA has the authority to take enforcement actions such as suspension or revocation of airworthiness certificates, further emphasising the importance of strict adherence to the directive.