AD 2018-14-05

This AD is effective August 13, 2018.

The Director of the Federal Register approved the incorporation by reference of certain publications listed in this AD as of August 13, 2018.

For service information identified in this final rule, contact Bombardier, Inc., 400 Côte-Vertu Road West, Dorval, Québec H4S 1Y9, Canada; telephone 514-855-5000; fax 514-855-7401; email thd.crj@aero.bombardier.com; internet http://www.bombardier.com. You may view this service information at the FAA, Transport Standards Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195. It is also available on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2018-0274.

Assata Dessaline, Aerospace Engineer, Avionics and Administrative Services Section, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7301; fax 516-794-5531; email 9-avs-nyaco-cos@faa.gov.

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Bombardier, Inc., Model BD-100-1A10 airplanes. The NPRM published in the Federal Register on April 13, 2018 (83 FR 16013). The NPRM was prompted by reports of fire incidents of the APU inlet, which caused tail cone damage after an initial failed APU start followed by two or more in-flight APU start attempts. The NPRM proposed to require modification of the APU ECU wiring harness.

We are issuing this AD to address failure of the APU inlet, which could result in a fire during flight.

Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada, has issued Canadian Airworthiness Directive CF-2017-26, dated July 31, 2017, (referred to after this as the Mandatory Continuing Airworthiness Information, or “the MCAI”), to correct an unsafe condition for certain Bombardier, Inc., Model BD-100-1A10 airplanes. The MCAI states:

APU inlet fire incidents causing tail cone damage have been reported after an initial failed APU start followed by two or more in-flight APU start attempts. Bombardier, Inc. (BA) has determined that the in-flight negative pressure differential at the APU inlet allows flash fires of residual fuel in the APU combustor to exit through the APU inlet.

As an interim mitigating action, BA has revised the affected aeroplane Aircraft Flight Manual (AFM) procedure for in-flight APU start to limit the number of APU start attempts.

To further address the safety concerns associated with in-flight APU inlet fire, BA is introducing a modification to the APU Electronic Control Unit (ECU) wiring harness that will prevent a second attempt to start the APU following a failed start in flight. This [Canadian] AD is issued to mandate compliance with BA Service Bulletin (SB) 100-49-04 or SB 350-49-001, as applicable, on affected aeroplanes.

You may examine the MCAI in the AD docket on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2018-0274.

We gave the public the opportunity to participate in developing this final rule. We received no comments on the NPRM or on the determination of the cost to the public.

We reviewed the relevant data and determined that air safety and the public interest require adopting this final rule as proposed, except for minor editorial changes. We have determined that these minor changes:

• Are consistent with the intent that was proposed in the NPRM for addressing the unsafe condition; and

• Do not add any additional burden upon the public than was already proposed in the NPRM.

Bombardier has issued Service Bulletin 100-49-04, dated March 29, 2017; and Service Bulletin 350-49-001, dated March 29, 2017. This service information describes a modification of the APU ECU harness. These documents are distinct since they apply to different airplane models in different configurations. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.

We estimate that this AD affects 198 airplanes of U.S. registry.

We estimate the following costs to comply with this AD:

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.

This AD is issued in accordance with authority delegated by the Executive Director, Aircraft Certification Service, as authorized by FAA Order 8000.51C. In accordance with that order, issuance of ADs is normally a function of the Compliance and Airworthiness Division, but during this transition period, the Executive Director has delegated the authority to issue ADs applicable to transport category airplanes and associated appliances to the Director of the System Oversight Division.

This AD will not have federalism implications under Executive Order 13132. This AD will 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 this AD:

(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),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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.

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

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

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