DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2018-0547; Product Identifier 2017-NM-091-AD]
RIN 2120-AA64

Airworthiness Directives; Bombardier, Inc., Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Proposed rule; withdrawal.

-----------------------------------------------------------------------

SUMMARY: The FAA is withdrawing a notice of proposed rulemaking (NPRM)
that proposed to adopt a new airworthiness directive (AD) that would
have applied to certain Bombardier, Inc., Model DHC-8-400 series
airplanes. The NPRM was prompted by reports of wear on fuel couplings,
bonding springs, and sleeves as well as fuel tube end ferrules and fuel
component end ferrules. The NPRM would have required repetitive
inspections of the existing clamshell coupling bonding wires, fuel
couplings, and associated sleeves for certain criteria, and replacement
as necessary. The NPRM would also have required repetitive inspections
of the fuel tube end ferrules, fuel component end ferrules, and ferrule
o-ring flanges for damage and wear, and rework as necessary. Since
issuance of the NPRM, the FAA determined that more restrictive
airworthiness limitations are also necessary, that an optional terminating
modification is appropriate for certain airplanes, and that the NPRM does
not adequately address the identified unsafe condition. Accordingly, the
NPRM is withdrawn.

DATES: The FAA is withdrawing the proposed rule published July 6, 2018
(83 FR 31488), as of August 28, 2019.

ADDRESSES:

Examining the AD Docket

You may examine the AD docket on the internet at http://www.regulations.
gov by searching for and locating Docket No. FAA-2018-0547;
or in person at Docket Operations between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays. The AD docket contains
this AD action, the regulatory evaluation, any comments received, and
other information. The street address for Docket Operations is U.S.
Department of Transportation, Docket Operations, M-30, West Building
Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC
20590.

FOR FURTHER INFORMATION CONTACT: Joseph Catanzaro, Aerospace Engineer,
Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart
Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7366; fax 516-
794-5531; email 9-avs-nyaco-cos@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

The FAA issued an NPRM that proposed to amend 14 CFR part 39 by
adding an AD that would apply to the specified products. The NPRM was
published in the Federal Register on July 6, 2018 (83 FR 31488). The
NPRM was prompted by reports of wear on fuel couplings, bonding
springs, and sleeves as well as fuel tube end ferrules and fuel
component end ferrules.

The NPRM proposed to require repetitive inspections of the existing
clamshell coupling bonding wires, fuel couplings, and associated
sleeves for certain criteria, and replacement as necessary. The NPRM
also proposed to require repetitive inspections of the fuel tube end
ferrules, fuel component end ferrules, and ferrule o-ring flanges for
damage and wear, and rework as necessary. The proposed actions were
intended to address wear on fuel couplings, bonding springs, and
sleeves as well as fuel tube end ferrules and fuel component end
ferrules, which could reduce the integrity of the electrical bonding
paths through the fuel line and components, and ultimately lead to fuel
tank ignition in the event of a lightning strike.

Actions Since the NPRM Was Issued

Since issuance of the NPRM, Bombardier developed a new optional
terminating modification for certain Model DHC-8-400 series airplanes
and issued associated service information. In addition, the
applicability for certain required actions was revised and more
restrictive airworthiness limitations related to the identified unsafe
condition were developed. In light of these changes, the FAA is
considering further rulemaking.

Withdrawal of the NPRM constitutes only such action and does not
preclude the FAA from further rulemaking on this issue, nor does it
commit the FAA to any course of action in the future.

FAA's Conclusions

Upon further consideration, the FAA has determined that the NPRM
does not adequately address the identified unsafe condition.
Accordingly, the NPRM is withdrawn.

Regulatory Findings

Since this action only withdraws an NPRM, it is neither a proposed
nor a final rule. This action therefore is not covered under Executive
Order 12866, the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

The Withdrawal

Accordingly, the notice of proposed rulemaking, Docket No. FAA-2018-
0547, which was published in the Federal Register on July 6, 2018 (83
FR 31488), is withdrawn.

Issued in Des Moines, Washington, on August 22, 2019. Suzanne Masterson,
Acting Director, System Oversight Division, Aircraft Certification
Service.