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# AIRWORTHINESS DIRECTIVE

The following airworthiness directive (AD) may be applicable to an aircraft which our records indicate is registered in your na me. ADs are issued pursuant to Canadian Aviation Regulation (CAR) 593 . Pursuant to CAR 605.84 and the further details of CAR Standard 625, Appendix H , the continuing airworthiness of a Canadian registered aircraft is contingent upon compliance with all applicable ADs. Failure to comply with the requirements of an AD may invalidat e the flight authorization of the aircraft. Alternative means of compliance shall be applied for in accordance with CAR 605.84 and the above-referenced Standard

. This AD has been issued by the Continuing Airworthiness Division (AARDG), National Aircraft Certification Branch, Transport Can ada, Ottawa, telephone 613 952-4357.

Pursuant to CAR 202.51 the registered owner of a Canadian aircraft shall, within seven days, notify the Minister in writing of any change of his or her name or address.

To request a change of address, contact the Civil Aviation Communica tions Centre (AARC)
at Place de Ville, Ottawa, Ontario K1A 0N8 , or 1-800-305-2059

, or www.tc.gc.ca/civilaviation/communications/centre/ address.asp

24-0022 (01-2005) 1/2 No

. CF-2009-15

Issue Date 17 April 2009

Number: CF-2009-15

Subject: Fuel System Safety - Introduction of Maintenance Tasks

Effective: 7 May 2009

Applicability: Viking Air Limited DHC-7-1, DHC-7- 100, DHC-7-101, DHC-7-102, DHC-7-103, DHC-7-110 and DHC-7-111 aircraft, all serial numbers.

Compliance: As indicated below, unless already accomplished.

Background: Viking Air Limited has completed a system sa fety review of the aircraft fuel system against fuel tank safety standards introduced in Chapter 525 of the Airworthiness Manualthrough Notice of Proposed Amendment (NPA) 2002-043. The identified noncompliances were then assessed using Tr ansport Canada Policy Letter No. 525-001, to determine if mandatory corrective action is required.

The assessment showed that supplemental maintenance tasks would be required to prevent potential ignition sources within the fuel system, which could result in a fuel tank explosion. Viking Air Limited has revis ed Chapter 5 of the DHC-7 Maintenance Manual, PSM 1-7-2, to introduce the required maintenance tasks.

Corrective

Actions: A. Incorporation of Fuel System Limitations (FSL) Tasks

Within 60 days after the effective date of this directive, revise the Transport Canada approved maintenance schedule by incorpor ating all the FSL tasks introduced in Chapter 5 of the DHC-7 Maintenance Manual, PSM 1-7-2, through the following Temporary Revisions (TR).

TR Number Task Number Description 5-106 FSL 01 to FSL 08 FSL Introduction, Rules and

Task List 5-107 FSL-01 Detailed Inspection of the

Electrical Isolation between the
Fuel Probe Conduit and the
Aircraft Structure 5-108 FSL-02 Detailed Inspection of the Electrical Bonding between the
Pressure Relief Valve Chassis and the Wing Fuel Tank
Structure 5-112 FSL-03 Special Detailed Inspection of the Dielectric Voltage Properties
of the Aluminum Loaded Primer and Enamel on the Wing Top
and Bottom SkinNo.

N ° CF-2009-15 2/2

5-113 FSL-04 and FSL-05 Detailed Visual Inspection of the Bonding Jumpers within the Fuel Tank for Condition, Security, Signs of Chafing and
Corrosion and Electrical Bonding Check of all Jumpers 5-109 FSL-06 Replacement of the Fuel Probe Wiring within the Fuel Tank 5-110 FSL-07 Functional Check of the Wing Dry Bay Drain Valve 5-111 FSL-08 Detailed Visual Inspection of the Fuel Containment Coating within the #4 Flap Track Canoe Fairing Landing Light Compartment and Visual Inspection of the Surge Bay

Drain Line

Note: Later revisions to the above- listed tasks introduced through Transport Canada-approved TRs or general revisions of the Maintenance Manual are also acceptable.

B. Phase-in time for Tasks FSL-01, FSL-02, FSL-03, FSL-04 and FSL-05

For aircraft that have, on the effective date of this directive, accumulated 12000 hours air time or more, carry out the initia l inspection of the above-listed tasks within 6000 hours airtime or 36 months, whichever occurs first.

C. Phase-in time for Tasks FSL-06

For aircraft that have, on the effective date of this directive, accumulated 34000 hours air time or more, carry out the above-listed task initially within 6000 hours airtime or 36 months, whichever occurs first.

D. Phase-in time for Tasks FSL-07

For all applicable aircraft, carry out the abov e-listed task initially within one month.

E. Phase-in time for Tasks FSL-08

For aircraft that have, on the effective dat e of this directive, accumulated 2000 hours air time or more, carry out the initial inspection of the above-listed task within 2000 hours airtime or 12 months, whichever occurs first.

Authorization: For Minister of Transport, In frastructure and Communities

Derek Ferguson Acting Chief, Continuing Airworthiness

Contact: Mr. Philip Tang, Continuing Airworthiness, Ottawa, telephone 613-952-4365, facsimile 613-996-9178 or e-mail philip.tang@tc.gc.ca or any Transport Canada Centre.