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 CAR 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.
DHC-3 (Otter) Series Aeroplanes
AD/DHC-3/38 Electrically Heated Engine Pneumatic Lines 12/2002
Applicability: DHC-3 “Turbo Otter” aircraft, all series, modified in accordance with A.M. Luton, United States Federal Aviation Administration (FAA) Supplemental Type Certificate (STC) No. SA3777NM or with Transport Canada Aviation equivalent Supplemental Type Approval No. SA89-32.
Requirement: 1. Inspect the electrical wiring to the P3 and Py engine pneumatic line heating blankets and to the P3 heater warning light to determine if they are wired in a parallel configuration. Sheet 1 of Drawing No. 20075 “Electrical System Schematic” Rev. I dated 10 October 2000 (hereafter referred to as ‘The Drawing’) as referenced in A.M. Luton Service Information Letter SIL-00-10-10 dated 22 March 2001 (hereafter referred to as the ‘SIL’) illustrates the correct wiring configuration. If the inspection determines that lines are correctly wired in a parallel configuration, proceed to Requirement 3.
Note 1: CASA recommends that the electrical inspection of the wiring include a continuity check of the heating blanket line(s) to ensure that they are serviceable. Then, after selecting the P3 heater switch to the “On” position, if the line(s) quickly feel warm to the touch, this is an additional indication that the line(s) are correctly configured.
2. If, as a result of the Requirement 2 inspection, it is determined that the P3 and Py engine pneumatic line heating blankets and the P3 heater warning light are incorrectly wired, modify the wiring to the configuration shown on The Drawing.
Note 2: CASA recommends that a similar test be performed as described in Note 1 after modifying the wiring.
3. Inspect the circuit breaker switch for the heated engine pneumatic lines circuit ensuring the following:
- If the engine installation utilizes both P3 and Py heated pneumatic lines, unless already accomplished, install a 7.5 Amp circuit breaker switch in accordance with The Drawing. Potter & Brumfield part number (P/N) W31- X2M1G-7.5, as referenced in the SIL, is an acceptable circuit breaker switch.
- If the engine installation utilizes only a P3 heated pneumatic line, unless already accomplished, install a 5.0 Amp circuit breaker switch in accordance with The Drawing. Potter & Brumfield P/N W31-X2M1G-5.0 is an acceptable circuit breaker switch.
DHC-3 (Otter) Series Aeroplanes
AD/DHC-3/38 (continued)
Note 3: Transport Canada AD CF-2002-38 refers.
Compliance: For Requirement 1 - Within 300 hours time in service after the effective date of this Directive, but no later than 31 January 2003.
For Requirement 2 - Before fur ther flight after the Requirement 1 inspection.
For Requirement 3 - Within 300 hours time in service after the effective date of this Directive, but no later than 31 January 2003.
This Airworthiness Directive becomes effective on 28 November 2002.
Background: The original issue and Revisions A to F on Sheet 1 of 3 of A.M. Luton Electrical System Schematic Drawing No. 20075 correctly shows the wiring to the electrical heating blankets on P3 and Py pneumatic lines and to the “Push to Test” function lights to be wired in parallel. Revisions G and H show incorrect (series) wiring; this incorrect (wired in series) wiring configuration can result in the current being absorbed by the light bulbs with no current for the heating blankets. Loss of pneumatic heating can result in loss of engine power or reverse propeller overspeed governing protection. Revision I corrects this mistake.
Barry James Reid McKay
Delegate of the Civil Aviation Safety Authority 18 October 2002
The above AD is notified in the Commonwealth of Australia Gazette on 6 November 2002.
Overview
The Civil Aviation Safety Authority (CASA) introduced the Airworthiness Directive (AD) AD/DHC-3/38 on 28 November 2002 to address safety concerns related to the electrical wiring configurations of the DHC-3 (Otter) series aeroplanes, specifically those modified under A.M. Luton FAA STC No. SA3777NM or Transport Canada equivalent Supplemental Type Approval No. SA89-32. This directive was issued under subregulation 39.1 (1) of the Civil Aviation Regulations 1998 and aims to correct the unsafe condition identified in the wiring of the electrically heated engine pneumatic lines, ensuring compliance with the correct configuration as illustrated in the referenced electrical system schematic. The primary objective of this directive is to prevent potential loss of engine power and reverse propeller overspeed governing protection, which could result from incorrect wiring configurations. The directive mandates inspections and modifications to the wiring and circuit breaker switches to rectify the unsafe condition, with specific compliance timelines set forth to ensure timely implementation.
Scope and Application
The Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998 targets DHC-3 "Turbo Otter" aircraft of all series that have been modified in accordance with the A.M. Luton FAA Supplemental Type Certificate (STC) No. SA3777NM or with the Transport Canada Aviation equivalent Supplemental Type Approval No. SA89-32. The directive mandates specific inspections and modifications to the electrical wiring and circuit breaker switches of the engine pneumatic line heating blankets and heater warning lights to rectify a wiring error that can potentially compromise engine performance and safety. The AD applies nationally across Australia, extending its regulatory oversight to all aircraft fitting the specified criteria, irrespective of their location within the country. The directive does not explicitly mention any exclusions or exemptions, implying that all applicable aircraft must adhere to its requirements. The CASA delegate's authority to issue such ADs is derived from subregulation 39.1 (1) of CAR 1998, and while the AD itself does not explicitly mention subordinate instruments extending or restricting its application, the CASA's broader regulatory framework likely includes provisions for such extensions or restrictions.
Key Provisions
The Airworthiness Directive (AD) AD/DHC-3/38, issued under subregulation 39.1(1) of the Civil Aviation Regulations 1998, specifically applies to DHC-3 "Turbo Otter" aircraft of all series that have been modified in accordance with either A.M. Luton United States Federal Aviation Administration (FAA) Supplemental Type Certificate (STC) No. SA3777NM or Transport Canada Aviation equivalent Supplemental Type Approval No. SA89-32. The AD requires certain actions to be taken to address an unsafe condition related to the electrical wiring of the engine pneumatic line heating blankets and the P3 heater warning light.
The primary requirements outlined in the AD are to inspect and, if necessary, modify the wiring configuration of the electrical system to ensure it is correctly set up in parallel, as illustrated in Drawing No. 20075 "Electrical System Schematic" Rev. I dated 10 October 2000. The inspection must be conducted to determine if the wiring is in a parallel configuration, and if not, the wiring must be modified accordingly. Additionally, the AD mandates the installation of appropriate circuit breaker switches based on the engine installation configuration, which is detailed in the AD and referenced in the Service Information Letter SIL-00-10-10 dated 22 March 2001.
The obligations under this AD include conducting the required inspections and modifications within specified timeframes. For Requirement 1, the inspection must be completed within 300 hours of time in service after the effective date of the AD, but no later than 31 January 2003. For Requirement 2, any necessary modifications must be made before further flight after the initial inspection. Requirement 3, which pertains to the installation of the circuit breaker switch, must also be completed within 300 hours of time in service after the AD's effective date, but no later than 31 January 2003.
Failure to comply with this AD may result in civil or criminal consequences. While the specific penalties are not detailed in the AD, non-compliance with ADs generally can lead to enforcement actions by the Civil Aviation Safety Authority (CASA). This may include fines, enforcement notices, or other regulatory actions designed to ensure the continued airworthiness of the aircraft. The potential severity of the penalties would depend on the nature and extent of the non-compliance.