2011-2613. Airworthiness Directives; Bombardier, Inc. Model DHC-8-400 Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

Bombardier Aerospace has completed a system safety review of the aeroplanes fuel system against fuel tank safety standards introduced in Chapter 525 of the Airworthiness Manual through Notice of Proposed Amendment (NPA) 2002-043 [which corresponds with the FAA's Special Federal Aviation Regulation (SFAR) 88]. The identified non-compliances were then assessed using Transport Canada Policy Letter No. 525-001, to determine if mandatory corrective action is required.

The assessment showed that a number of modifications to the fuel system are required to mitigate unsafe conditions that could result in potential ignition source within the fuel system.

The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.

DATES:

We must receive comments on this proposed AD by March 24, 2011.

ADDRESSES:

You may send comments by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-40, 1200 New Jersey Avenue, SE., 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., Q-Series Technical Help Desk, 123 Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada; telephone [phone]; fax [phone]; e-mail [e-mail]; Internet http://www.bombardier.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov;​; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

James Delisio, Aerospace Engineer, Propulsion and Services Branch, ANE-173, 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 send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2011-0036; Directorate Identifier 2010-NM-230-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD based on those comments.

We will post all comments we receive, without change, to http://www.regulations.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada, has issued Canadian Airworthiness Directive CF-2010-31, dated September 3, 2010 (referred to after this as “the MCAI”), to correct an unsafe condition for the specified products. The MCAI states:

Bombardier Aerospace has completed a system safety review of the aeroplanes fuel system against fuel tank safety standards introduced in Chapter 525 of the Airworthiness Manual through Notice of Proposed Amendment (NPA) 2002-043 [which corresponds with the FAA's Special Federal Aviation Regulation (SFAR) 88]. The identified non-compliances were then assessed using Transport Canada Policy Letter No. 525-001, to determine if mandatory corrective action is required.

The assessment showed that a number of modifications to the fuel system are required to mitigate unsafe conditions that could result in potential ignition source within the fuel system.

The Bombardier modifications include:

• Modsum 4-126330, “Fuel Tank System Design Left and Right Side (SFAR 88) Retrofit.” The retrofit includes replacing certain fittings, couplings, o-rings, gaskets, fuel adapter, and other related components with new, improved parts; applying alodine 1132 to certain areas of a wing rib and a wing spar; and replacing a certain doubler on the front wing spar with a new, improved doubler.
• Modsum 4-126366, “Fuel Tank System and Fuel Indication—Wiring Identification, Segregation and Installation (High Level Sensor and Fuel Quantity Indication)—Retrofit.” The retrofit includes adding new wiring with protective sleeving, reworking existing wiring, labeling and separating the fuel quantity indicating (FQI) wiring and high level sensor wiring from other wiring, enhancing the electro-magnetic interference (EMI) shielding of the wiring connected to the vent valve position switch, and installing additional provisions (bulkhead brackets) for wiring clips in the center fuselage.
• Modsum 4-901425, “Fuel Feed to APU—Replacement of Couplings in Center Wing Left Side—SFAR 88.”
• Modsum 4-126370, “Fuel Tank System—Enhance Protective Covering for Electrical Cable Assembly,” which includes reworking the contact area on the rib at Yw-42.000 to ensure adequate electrical bonding, installing spiral wrap on certain cable assemblies where existing spiral wrap does not extend 4 inches past the tie mounts, applying a dome seal on thread openings on a high level sensor, and installing fuel grommets at certain locations.
• Modsum 4-113580, “Fuel Indication—High Level Sensor—Application of Sealant to exposed end of Sensor Terminal Block Screws—Special Inspection and Rectification,” which includes doing a detailed inspection of the high level sensor for correct sealant coverage (`dome seal') on the terminal screws, and applying sealant if necessary.

You may obtain further information by examining the MCAI in the AD docket.

The FAA has examined the underlying safety issues involved in fuel tank explosions on several large transport airplanes, including the adequacy of existing regulations, the service history of airplanes subject to those regulations, and existing maintenance practices for fuel tank systems. As a result of those findings, we issued a regulation titled “Transport Airplane Fuel Tank System Design Review, Flammability Reduction and Maintenance and Inspection Requirements” (66 FR 23086, May 7, 2001). In addition to new airworthiness standards for transport airplanes and new maintenance requirements, this rule included Special Federal Aviation Regulation No. 88 (“SFAR 88,” Amendment 21-78, and subsequent Amendments 21-82 and 21-83).

Among other actions, SFAR 88 requires certain type design (i.e., type certificate (TC) and supplemental type certificate (STC)) holders to substantiate that their fuel tank systems can prevent ignition sources in the fuel tanks. This requirement applies to type design holders for large turbine-powered transport airplanes and for subsequent modifications to those airplanes. It requires them to perform design reviews and to develop design changes and maintenance procedures if their designs do not meet the new fuel tank safety standards. As explained in the preamble to the rule, we intended to adopt airworthiness directives to mandate any changes found necessary to address unsafe conditions identified as a result of these reviews.

In evaluating these design reviews, we have established four criteria intended to define the unsafe conditions associated with fuel tank systems that require corrective actions. The percentage of operating time during which fuel tanks are exposed to flammable conditions is one of these criteria. The other three criteria address the failure types under evaluation: single failures, single failures in combination with a latent condition(s), and in-service failure experience. For all four criteria, the evaluations included consideration of previous actions taken that may mitigate the need for further action.

We have determined that the actions identified in this AD are necessary to reduce the potential of ignition sources inside fuel tanks, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.

Relevant Service Information

Bombardier has issued Service Bulletins:

• 84-57-09, Revision B, dated September 3, 2008;
• 84-28-04, Revision B, dated October 21, 2009;
• 84-28-05, dated June 28, 2006;
• 84-28-03, Revision C, dated May 15, 2009; and
• 84-28-07, dated August 1, 2008.

Bombardier has also issued Fuel Systems Limitation (FSL) Task 284000-417 in Section 4-1, Fuel System Limitations, of Part 2—Airworthiness Limitation Items, Revision 5, dated April 21, 2010, of Bombardier Q400 Dash 8 Maintenance Requirements Manual, PSM 1-84-7.

The actions described in this service information are intended to correct the unsafe condition identified in the MCAI.

FAA's Determination and Requirements of This Proposed AD

This product has been approved by the aviation authority of another country, and is approved for operation in the United States. Pursuant to our bilateral agreement with the State of Design Authority, we have been notified of the unsafe condition described in the MCAI and service information referenced above. We are proposing this AD because we evaluated all pertinent information and determined an unsafe condition exists and is likely to exist or develop on other products of the same type design.

Differences Between This AD and the MCAI or Service Information

We have reviewed the MCAI and related service information and, in general, agree with their substance. But we might have found it necessary to use different words from those in the MCAI to ensure the AD is clear for U.S. operators and is enforceable. In making these changes, we do not intend to differ substantively from the information provided in the MCAI and related service information.

We might also have proposed different actions in this AD from those in the MCAI in order to follow FAA policies. Any such differences are highlighted in a Note within the proposed AD.

Costs of Compliance

Based on the service information, we estimate that this proposed AD would affect about 67 products of U.S. registry. We also estimate that it would take about 526 work-hours per product to comply with the basic requirements of this proposed AD. The average labor rate is $85 per work-hour. Required parts would cost about $37,696 per product. Where the service information lists required parts costs that are covered under warranty, we have assumed that there will be no charge for these costs. As we do not control warranty coverage for affected parties, some parties may incur costs higher than estimated here. Based on these figures, we estimate the cost of the proposed AD on U.S. operators to be $5,521,202, or $82,406 per product.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. 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.

We are issuing this rulemaking 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 rulemaking action.

Regulatory Findings

We 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 this 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 and placed it in the AD docket.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• 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 AD:

Bombardier, Inc.: Docket No. FAA-2011-0036; Directorate Identifier 2010-NM-230-AD.

Comments Due Date

(a) We must receive comments by March 24, 2011.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes, certificated in any category; with serial numbers (S/N) 4003, 4004, 4006, and 4008 through 4205 inclusive.

Subject

(d) Air Transport Association (ATA) of America Code 28: Fuel.

Reason

(e) The mandatory continuing airworthiness information (MCAI) states:

Bombardier Aerospace has completed a system safety review of the aeroplanes fuel system against fuel tank safety standards introduced in Chapter 525 of the Airworthiness Manual through Notice of Proposed Amendment (NPA) 2002-043 [which corresponds with the FAA's Special Federal Aviation Regulation (SFAR) 88]. The identified non-compliances were then assessed using Transport Canada Policy Letter No. 525-001, to determine if mandatory corrective action is required.

The assessment showed that a number of modifications to the fuel system are required to mitigate unsafe conditions that could result in potential ignition source within the fuel system.

Compliance

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

Actions Applicable to Airplanes Having S/N 4003, 4004, 4006 & 4008 Through 4118

(g) For airplanes having S/Ns 4003, 4004, 4006, and 4008 through 4118 inclusive: Within 6,000 flight hours after the effective date of this AD, incorporate the modifications required in paragraphs (g)(1), (g)(2), and (g)(3) of this AD, as applicable.

(1) Incorporate Bombardier Modsum 4-126330, “Fuel Tank System Design Left and Right Side (SFAR 88) Retrofit,” by doing all the applicable actions in the Accomplishment Instructions of Bombardier Service Bulletin 84-57-09, Revision B, dated September 3, 2008.

(2) Incorporate Bombardier Modsum 4-126366, “Fuel Tank System and Fuel Indication—Wiring Identification, Segregation and Installation (High Level Sensor and Fuel Quantity Indication)—Retrofit,” by doing all the applicable actions in the Accomplishment Instructions of Bombardier Service Bulletin 84-28-04, Revision B, dated October 21, 2009.

(3) For airplanes on which Bombardier Modsum 4-302000, “Standard Option—APU Installation,” has been installed: Incorporate Bombardier Modsum 4-901425, “Fuel Feed to APU—Replacement of Couplings in Center Wing Left Side—SFAR 88,” by doing all the applicable actions in the Accomplishment Instructions of Bombardier Service Bulletin 84-28-05, dated June 28, 2006.

(h) For airplanes having S/Ns 4003, 4004, 4006, and 4008 through 4118 inclusive, do Bombardier Fuel System Limitation (FSL) Task 284000-417 (Functional Check of the Fuel Tank Components and Plumbing Lines for Electrical Bonding) contained in Section 4-1, Fuel System Limitations, of Part 2—Airworthiness Limitation Items, Revision 5, dated April 21, 2010, of Bombardier Q400 Dash 8 Maintenance Requirements Manual, PSM 1-84-7, at the applicable times specified in paragraphs (h)(1) and (h)(2) of this AD. Where the task specifies contacting Bombardier for technical assistance, this AD requires repairs/rework actions in accordance with a method approved by the Manager, New York Aircraft Certification Office (ACO), FAA, or Transport Canada Civil Aviation (TCCA) (or its delegated agent).

(1) Except as provided in paragraphs (h)(1)(i) and (h)(1)(ii) of this AD, for airplanes that have incorporated either Bombardier Modsum 4-126330 or 4-901425 prior to the effective date of this AD: Do Bombardier FSL Task 284000-417 within 6,000 flight hours after the effective date of this AD.

(i) Airplanes on which Bombardier FSL Task 284000-417 was successfully completed after incorporation of Bombardier Modsum 4-126330 or 4-901425 do not need to comply with the requirements of paragraph (h) of this AD.

(ii) Airplanes on which Bombardier Modsum 4-126330 or 4-901425 was incorporated during manufacturing of the airplane do not need to comply with the requirements of paragraph (h) of this AD.

(2) For airplanes on which neither Bombardier Modsum 4-126330 nor 4-901425 were incorporated before the effective date of this AD: Do Bombardier FSL Task 284000-417 upon completion of the incorporation of Bombardier Modsum 4-126330 and, if applicable, Bombardier Modsum 4-901425.

Actions Applicable to Airplanes S/N 4003, 4004, 4006 & 4008 Through 4118 Inclusive, Manufactured Before September 21, 2005

(i) For airplanes having S/N 4003, 4004, 4006, and 4008 through 4118 inclusive, on which the date of issuance of the original Canadian standard airworthiness certificate or the date of issuance of the original Canadian export certificate of airworthiness is before September 21, 2005: Within 6,000 flight hours after the effective date of this AD, incorporate Bombardier Modsum 4-126370, “Fuel Tank System—Enhance Protective Covering for Electrical Cable Assembly,” by doing all the applicable actions in the Accomplishment Instructions of Bombardier Service Bulletin 84-28-03, Revision C, dated May 15, 2009.

Actions Applicable to Airplanes S/N 4003, 4004, 4006 & 4008 Through 4118 Inclusive, Manufactured on or After September 21, 2005

(j) For airplanes having S/Ns 4003, 4004, 4006, and 4008 through 4118 inclusive, on which the date of issuance of the original Canadian standard airworthiness certificate or the date of issuance of the original Canadian export certificate of airworthiness is on or after September 21, 2005: Within 12,000 flight hours after the effective date of this AD, incorporate Bombardier Modsum 4-126370, “Fuel Tank System—Enhance Protective Covering for Electrical Cable Assembly,” by doing all the applicable actions in the Accomplishment Instructions of Bombardier Service Bulletin 84-28-03, Revision C, dated May 15, 2009.

Actions Applicable to Airplanes S/N 4119 Through 4205 Inclusive

(k) For airplanes having S/N 4119 through 4205 inclusive: Within 6,000 flight hours after the effective date of this AD, incorporate Bombardier Modsum 4-113580, “Fuel Indication—High Level Sensor—Application of Sealant to Exposed End of Sensor Terminal Block Screws—Special Inspection and Rectification,” by doing all the applicable actions in the Accomplishment Instructions of Bombardier Service Bulletin 84-28-07, dated August 1, 2008.

Credit for Actions Accomplished in Accordance With Previous Service Information

(l) Incorporation of Bombardier Modsum 4-126330 prior to the effective date of this AD according to the instructions contained in Bombardier Service Bulletin 84-57-09, Revision A, dated March 19, 2007, meets the requirements of paragraph (g)(1) of this AD.

(m) Incorporation of Bombardier Modsum 4-126366 prior to the effective date of this AD according to the instructions contained in Bombardier Service Bulletin 84-28-04, dated June 29, 2006; or Revision A, dated November 15, 2006; meets the requirements of paragraph (g)(2) of this AD.

(n) Incorporation of Bombardier Modsum 4-126370 prior to the effective date of this AD according to instructions contained in Bombardier Service Bulletin 84-28-03, Revision B, dated October 18, 2006, meets the requirements of paragraphs (i) and (j) of this AD.

FAA AD Differences

Note 1:

This AD differs from the MCAI and/or service information as follows: The MCAI specifies to do Bombardier FSL Task 28400-417, but does not specify what to do if the functional check finds that measured resistance exceeds the specified values. This AD requires contacting the Manager, New York ACO, FAA, or TCCA (or its delegated agent) for repair/rework instructions.

Other FAA AD Provisions

(o) The following provisions also apply to this AD:

(1) Alternative Methods of Compliance (AMOCs): The Manager, ANE-170, New York ACO, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to Attn: Program Manager, Continuing Operational Safety, FAA, New York ACO, 1600 Stewart Avenue, Suite 410, Westbury, New York 11590; telephone [phone]; fax [phone]. Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office. The AMOC approval letter must specifically reference this AD.

(2) Airworthy Product: For any requirement in this AD to obtain corrective actions from a manufacturer or other source, use these actions if they are FAA-approved. Corrective actions are considered FAA-approved if they are approved by the State of Design Authority (or their delegated agent). You are required to assure the product is airworthy before it is returned to service.

Related Information

(p) Refer to MCAI Canadian Airworthiness Directive CF-2010-31, dated September 3, 2010; Bombardier Task 284000-417 in Section 4-1, Fuel System Limitations, of Part 2—Airworthiness Limitation Items, Revision 5, dated April 21, 2010, of Bombardier Q400 Dash 8 Maintenance Requirements Manual, PSM 1-84-7; and the Bombardier service bulletins identified in Table 1 of this AD; for related information.

Table 1—Relevant Service Information

Bombardier Service Bulletin—	Revision—	Dated—
84-28-03	C	May 15, 2009.
84-28-04	B	October 21, 2009.
84-28-05	Original	June 28, 2006.
84-28-07	Original	August 1, 2008.
84-57-09	B	September 3, 2008.

Dated: Issued in Renton, Washington, on January 31, 2011.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.