05-6253. Airworthiness Directives; Bombardier Model DHC-8-102, -03, -106, -201, -202, -301, -311, and -315 Airplanes

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Bombardier Model DHC-8-102, -103, -106, -201, -202, -301, -311 and -315 airplanes. This proposed AD would require installation of check valves in Numbers 1 and 2 hydraulic systems, removal of the filters from the brake shuttle valves, and removal of the internal garter spring from the brake shuttle valves. This proposed AD results from two instances of brake failure due to the loss of hydraulic fluid from both Numbers 1 and 2 hydraulic systems and one incident of brake failure due to filter blockage in the shuttle valve. We are proposing this AD to prevent the loss of hydraulic power from both hydraulic systems which could lead to reduced controllability of the airplane; and to prevent brake failure which could result in the loss of directional control on the ground and consequent departure from the runway during landing.

DATES:

We must receive comments on this proposed AD by April 29, 2005.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., Nassif Building, room PL-401, Washington, DC 20590.
• By fax: [phone].
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Bombardier, Inc., Bombardier Regional Aircraft Division, 123 Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada.

You can examine the contents of this AD docket on the Internet at http://dms.dot.gov,, or in person at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC. This docket number is FAA-2005-20756; the directorate identifier for this docket is 2004-NM-52-AD.

FOR FURTHER INFORMATION CONTACT:

Ezra Sasson, Aerospace Engineer, Airframe and Propulsion Branch, ANE-171, FAA, New York Aircraft Certification Office, 1600 Stewart Avenue, suite 410, Westbury, New York 11590; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2005-20756; Directorate Identifier 2004-NM-52-AD at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments submitted by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of our docket Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You can review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov.

Examining the Docket

You can examine the AD docket on the Internet at http://dms.dot.gov,, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone [phone]) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

Transport Canada Civil Aviation (TCCA), which is the airworthiness authority for Canada, notified us that an unsafe condition may exist on certain Bombardier Model DHC-8-102, -103, -106, -201, -202, -301, -311, and -315 airplanes. TCCA advises that there have been two instances during which the Numbers 1 and 2 hydraulic systems power was lost due to a hydraulic leak downstream of one of the brake shuttle valves. Investigation revealed that a minor leak in one of the brake units allowed the Number 2 hydraulic system fluid to deplete. In addition, the shuttle valve internal garter spring had also failed. This failure allowed the Number 1 hydraulic system fluid to also deplete through the same brake unit. This condition, if not corrected, could result in loss of hydraulic power from both hydraulic systems, which could lead to reduced controllability of the airplane.

An additional incident has been reported of a brake seizure and subsequent wheel assembly fire while the airplane was taxiing. An investigation revealed that hydraulic pressure remained applied to the brake unit even after brake release. It was determined that the dislodging of the 10-micron filter in the brake shuttle valve had blocked the valve port and prevented hydraulic fluid flow from the brake. Brake failure could result in the loss of directional control on the ground and consequent departure from the runway during landing.

Relevant Service Information

Bombardier Inc. has issued Service Bulletin S.B. 8-29-36, Revision “B,” dated January 6, 2003, that describes procedures for installing check valves in the Numbers 1 and 2 hydraulic systems by incorporating Modsum 8Q101320. Bombardier has also issued S.B. 8-29-37, Revision “A,” dated September 19, 2003, that provides instructions for incorporating Modsum 8Q101316 to remove the filter assemblies and internal garter spring, and S.B. 8-29-39, dated July 14, 2003, that includes instructions for incorporating Modsum 8Q101422 to remove the filter assemblies. Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition. TCCA mandated the service information and issued Canadian airworthiness directive CF-2004-02, dated February 9, 2004, to ensure the continued airworthiness of these airplanes in Canada.

FAA's Determination and Requirements of the Proposed AD

These airplane models are manufactured in Canada and are type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, TCCA has kept the FAA informed of the situation described above. We have examined TCCA's findings, evaluated all pertinent information, and determined that we need to issue an AD for products of this type design that are certificated for operation in the United States.

Therefore, we are proposing this AD, which would require installation of check valves in Numbers 1 and 2 hydraulic systems, removal of filters from the brake shuttle valves and removal of the internal garter spring from the brake shuttle valves. The proposed AD would require you to use the service information described previously to perform these actions, except as discussed under “Differences Between the Proposed AD and Canadian Airworthiness Directive.”

Differences Between the Proposed AD and Canadian Airworthiness Directive

Although the Canadian airworthiness directive recommends, for airplanes that removed the filters from the brake shuttle valve, removal of the internal garter spring at the next overhaul of each brake shuttle valve, we have determined that a specific compliance time is needed. In developing appropriate compliance times for this proposed AD, we considered not only the manufacturer's recommendation, but also the degree of urgency associated with addressing the subject unsafe condition, and the average utilization of the affected fleet. Considering these factors, we find that after removing the filters, a compliance time of 40,000 flight hours for the removal of the internal garter spring is warranted. We have coordinated this issue with TCCA.

Costs of Compliance

The following table provides the estimated costs for U.S. operators to comply with this proposed AD:

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per airplane	Number of U.S.-registered airplanes	Average fleet cost
Installation of check valves in Numbers 1 and 2 hydraulic systems	3	$65	$279-$405	$444-$600	179	$79,476-$107,400
Removal of filters and internal garter springs from brake shuttle valves	3	65	252-1,360	447-1,555	179	80,013-278,345

Authority for This Rulemaking

The FAA's authority to issue rules regarding aviation safety is found in Title 49 of the United States Code. Subtitle I, Section 106, describes the authority of the FAA Administrator. subtitle VII, Aviation Programs, describes in more detail the scope of the agency's authority.

This rulemaking is promulgated under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this proposed AD.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify that the proposed regulation:

1. Is not a “significant regulatory action” under Executive Order 12866;

2. Is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and

3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):

Bombardier, Inc. (Formerly de Havilland, Inc.): Docket No. FAA-2005-20756; Directorate Identifier 2004-NM-52-AD.

Comments Due Date

(a) The Federal Aviation Administration must receive comments on this AD action by April 29, 2005.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Bombardier Model DHC-8-102, -103, -106, -201, -202, -301, -311, and -315, certificated in any category; serial numbers 003 through 593 inclusive.

Unsafe Condition

(d) This AD results from two instances of brake failure due to the loss of hydraulic fluid from both Numbers 1 and 2 hydraulic systems and one incident of brake failure due to filter blockage in the shuttle valve. We are proposing this AD to prevent the loss of hydraulic power from both hydraulic systems which could lead to reduced controllability of the airplane; and to prevent brake failure which could result in the loss of directional control on the ground and consequent departure from the runway during landing.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Installation of Check Valves in Numbers 1 and 2 Hydraulic Systems

(f) Within 12 months after the effective date of this AD, install check valves in the Numbers 1 and 2 hydraulic return systems by incorporating Modsum 8Q101320 in accordance with the Accomplishment Instructions of Bombardier Service Bulletin S.B. 8-29-36, Revision ‘B,’ dated January 6, 2003.

Removal of Filters and Internal Garter Spring From the Brake Shuttle Valves

(g) Within 12 months after the effective date of this AD, modify the brake shuttle valves, part number (P/N) 5084-1, by doing the actions in either paragraph (g)(1) or (g)(2) of this AD. The installation specified in paragraph (f) of this AD must be done prior to doing any actions in accordance with Bombardier Service Bulletin S.B. 8-29-37, Revision ‘A,’ dated September 19, 2003 (Modsum 8Q101316) that are specified in paragraphs (g)(1) and (g)(2) of this AD.

(1) Remove the filter assemblies by incorporating Modsum 8Q101422 in accordance with the Accomplishment Instructions of Bombardier Service Bulletin S.B. 8-29-39, dated July 14, 2003; and within 40,000 flight hours after removing the filter assemblies, remove the internal garter spring by incorporating Modsum 8Q101316 in accordance with the Accomplishment Instructions of Bombardier Service Bulletin S.B. 8-29-37, Revision ‘A,’ dated September 19, 2003.

(2) Remove the filter assemblies and internal garter spring by incorporating Modsum 8Q101316 in accordance with the Accomplishment Instructions of Bombardier Service Bulletin S.B. 8-29-37, Revision ‘A,’ dated September 19, 2003.

Note 1:

You can mix shuttle valves that have incorporated either Modsum 8Q101316 or 8Q101422 on the same airplane.

Actions Accomplished According to Previous Issues of Service Bulletins

(h) Installations accomplished before the effective date of this AD according to Bombardier Service Bulletin S.B. 8-29-36, dated December 6, 2002, and Revision ‘A,’ dated December 12, 2002, are considered acceptable for compliance with the corresponding installation specified in paragraph (f) of this AD.

(i) Removals of the filters and internal garter springs accomplished before the effective date of this AD according to Bombardier Service Bulletin S.B. 8-29-37, dated July 15, 2003, are considered acceptable for compliance with the corresponding removals specified in paragraph (g) of this AD.

Alternative Methods of Compliance (AMOCs)

(j) The Manager, New York Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

Related Information

(k) Canadian airworthiness directive CF-2004-02, dated February 9, 2004, also addresses the subject of this AD.

Issued in Renton, Washington, on March 22, 2005.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.