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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) 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 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 Communicat ions 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-2010-06

Issue Date 24 February 2010

Number: CF-2010-06

Subject: In-Flight Loss of Cabin Pressurizati on: Blockage of the Safety Valve Cabin Pressure-Sensing Port

Effective: 19 March 2010

Applicability: Bombardier Inc. Model: BD-100-1A10, Serial Numbers (S/Ns) 20001 through 20274.

Compliance: As indicated below.

Background: Investigation of a recent high altitude lo ss of cabin pressurization on a BD-100-1A10 aircraft determined that it was caused by a partial blockage of a safety valve cabin pressure-sensing port, in conjunction with a dormant failure/leakage of the safety valve manometric capsule. The blockage, caused by accumulation of lint/dust on the grid of the port plug, did not allow sufficient airflo w through the cabin pressure-sensing port to compensate for the rate of leakage from t he manometric capsule, resulting in the opening of the safety valve. It was also determined that failure of the manometric capsule alone would not result in the opening of the safety valve.

This directive mandates a revision of t he maintenance schedule, the cleaning of the safety valves, the removal of material fr om the area surrounding the safety valves and the modification of the safety valves with a gridless cabin pressure-sensing port plug.

Corrective

Actions: Part I – Revision of the Maintenance Schedule

Applicable to BD-100-1A10 aircraft, S/Ns 20001 through 20274.

Within 30 days of the effective date of th is directive, unless already accomplished:

Revise the Transport Canada approved main tenance schedule by incorporating the repetitive functional test of the safety va lves (Task Number 21-31-09-101) and repetitive discard of the safety valve filters (T ask number 21-31-09-102) contained in BD-100 Time Limits/Maintenance Checks (TLMC), Temporary Revision (TR) 5-2-53, dated 1 October 2009,

Notes: 1. BD-100 TLMC TR 5-2-53 contains phase-in schedules, as necessary, for the initial functional test of the safety valv es and the initial discard of the safety

valve filters on aircraft that have exceeded the initial task intervals.

2. Compliance with superseding TRs or later revisions of the BD-100 TLMC, approved by Transport Canada, also satisf ies the requirements of Part I of

this directive.

Part II – Initial Cleaning of the Safety Valves, including the Cabin PressureSensing Port Plugs, and Removal of Surrounding Material

Applicable to BD-100-1A10 aircraft, S/Ns 20003 through 20173, 20176 and 20177.

Within 50 hours air time after the effectiv e date of this direct ive, unless already accomplished:No.

N ° CF-2010-06 2/2

Inspect both safety valves and the su rrounding areas, clean the safety valves (including the cabin pressure-sensing port plugs) and remove surrounding material, as necessary, in accordance with the Accomplishm ent Instructions in Bombardier Service Bulletin (SB) 100-25-14, dated 30 June 2008, or SB 100-25-21, dated 30 June 2008, whichever is applicable, or later revi sions approved by the Chief, Continuing Airworthiness, Transport Canada.

Part III - Initial Cleaning of the Safety Valve Cabin Pressure-Sensing Port Plugs

Applicable to BD-100-1A10 aircraft, S/Ns 20174, 20175, 20178 through 20189, 20191 through 20228, 20230 through 20232, 20235, 20237, 20238, 20241, 20244, 20247, 20249 through 20251, 20254, 20256 and 20259.

Within 50 hours air time after the effectiv e date of this direct ive, unless already accomplished:

Clean the cabin pressure-sensing port plug in bot h safety valves, in accordance with the Accomplishment Instructions in Paragraph 2.B ., Part A, of Bombardier Alert Service Bulletin (ASB) A100-21-08, dated 18 June 2009, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

Part IV - Repetitive Cleaning of the Safety Valve Cabin Pressure-Sensing Port Plugs

Applicable to BD-100-1A10 aircraft, S/Ns 20003 through 20189, 20191 through 20228, 20230 through 20232, 20235, 20237, 20238, 20241, 20244, 20247, 20249 through
20251, 20254, 20256 and 20259.

Within 50 hours air time after the effectiv e date of this directive and subsequently no later than every 50 hours air time until Part V of this directive is accomplished:

Clean the cabin pressure-sensing port plug in bot h safety valves, in accordance with the Accomplishment Instructions in Paragraph 2. B., Part A, of Bombardier ASB A100-21-08, dated 18 June 2009, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

Part V – Modification: Replacement of the Safety Valve Cabin Pressure-Sensing Port Plugs and Reidentification of the Safety Valves

Applicable to BD-100-1A10 aircraft, S/Ns 20003 through 20189, 20191 through 20228, 20230 through 20232, 20235, 20237, 20238, 20241, 20244, 20247, 20249 through
20251, 20254, 20256 and 20259.

Within 12 months after the effective date of this directive, unless already accomplished: Replace the cabin pressure-sensing port plug Part Number (P/N) 2844-060 in both safety valves with a new gridless plug P/ N 2844-19 and reidentify the safety valves, in accordance with the Accomplishment Instru ctions in Paragraph 2.C., Part B, of Bombardier ASB A100-21-08, dated 18 June 2009, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

Authorization: For Minister of Transport, In frastructure and Communities



### ORIGINAL SIGNED BY

Derek Ferguson Chief, Continuing Airworthiness

Contact: Mr. Richard Topham, Continuing Airworthiness, Ottawa, telephone 613-952-4357,

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

Canada Centre.