Transport Transports 

Canada Canada

 TP 7245E

 

AIRWORTHINESS DIRECTIVE

The following airworthiness directive (AD) may be applicable to an aircraft which our records indicate is registered in your name. ADs are issued pursuant to Canadian 

Aviation Regulation (CAR) 521 Division X. 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 invalidate 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 Canada, 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 Communications 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-2012-09

Issue Date 

 15 February 2012 

Number: CF-2012-09 

Subject: Loss of the 400Hz Fixed Frequency System Due To Multiple Inverter Failures 

Effective: 27 February 2012 

Applicability: Bombardier Inc. DHC-8 Aeroplane Models 102, 103, 106, 201, 202, 301, 311, 314 and 

315, Serial Numbers 002 through 672 

Compliance: As indicated below, unless already accomplished. 

Background: There have been several reported occurrences of the loss of the 400Hz Fixed Frequency 

System, leading to the loss of power to the Left 115VAC bus, the Right 115VAC bus, the 

Left 26VAC bus, the Right 26VAC bus and all systems serviced by these four electrical 

buses. The loss of the 400Hz Fixed Frequency System has been attributed to a failure of 

one or two static inverters, which resulted in the loss of the remaining inverters. The loss

of systems serviced by the four fixed frequency electrical buses creates an unsafe 

condition due to the loss of a number of the pilot’s and co-pilot’s flight instruments, in 

addition to the other avionics systems. 

This Airworthiness Directive (AD) mandates the wiring modification to untie the 400Hz 

inverters and additional Airworthiness Limitation tasks introduced as a result of this 

modification. 

Corrective 

Actions: 

Part I - Wiring Modifications 

Within 6000 hours air time or 36 months, whichever occurs first, from the effective date of 

this AD, incorporate the wiring modifications in accordance with Bombardier Service 

Bulletin (SB) 8-24-87, Revision A, dated 5 October 2011, or later revisions approved by 

the Chief, Continuing Airworthiness, Transport Canada. 

Incorporation of SB 8-24-87, Initial Issue, dated 26 May 2011, also meets the 

requirements of Part I of this AD. 

Part II - Amendment to the Maintenance Schedule 

Within 30 days from the effective date of this AD, revise the Transport Canada approved 

maintenance schedule to incorporate Airworthiness Limitation task 2420/13 as 

introduced by the applicable Temporary Revisions (TR) of the Dash-8 Maintenance 

Program Manual – Airworthiness Limitations List: 
No.

N° CF-2012-09 2/2 

Dash 8 Series TR Number Date 

Series 100 TR AWL-117 08 April 2011 

Series 200 TR AWL 2-48 08 April 2011 

Series 300 TR AWL 3-118 08 April 2011 

Authorization: For the Minister of Transport, Infrastructure and Communities 

ORIGINAL SIGNED BY

Derek Ferguson 

Chief, Continuing Airworthiness 

Contact: Miss Helen Tsai, Continuing Airworthiness, Ottawa, telephone 613-952-4357, facsimile 

613-996-9178 or e-mail CAWWEBFeedback@tc.gc.ca or any Transport Canada Centre.