[Federal Register Volume 63, Number 219 (Friday, November 13, 1998)]
[Proposed Rules]
[Page 63423]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-30334]


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 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
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  Federal Register / Vol. 63, No. 219 / Friday, November 13, 1998 / 
Proposed Rules  

[[Page 63423]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-134-AD]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model CL-600-2B19 (Regional 
Jet Series 100) Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Proposed rule; withdrawal.

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SUMMARY: This action withdraws a notice of proposed rulemaking (NPRM) 
that proposed a new airworthiness directive (AD), applicable to certain 
Bombardier Model CL-600-2B19 (Regional Jet Series 100) series 
airplanes. That action would have required repetitive inspections of 
the inboard and outboard flap actuators to measure the rotational 
freedom of the actuator ball screw adjacent to the actuator housing, 
and replacement of the flap actuators with new or serviceable 
actuators, if necessary. Since the issuance of the NPRM, the Federal 
Aviation Administration (FAA) has received new data pertaining to this 
issue and is undertaking alternative rulemaking action. Accordingly, 
the proposed rule is withdrawn.

FOR FURTHER INFORMATION CONTACT: Anthony E. Gallo, Aerospace Engineer, 
Systems and Flight Test Branch, ANE-172, FAA, Engine and Propeller 
Directorate, New York Aircraft Certification Office, 10 Fifth Street, 
Third Floor, Valley Stream, New York 11581; telephone (516) 256-7510; 
fax (516) 568-2716.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to add a new airworthiness 
directive (AD), applicable to certain Bombardier Model CL-600-2B19 
(Regional Jet Series 100) series airplanes, was published in the 
Federal Register on June 8, 1998 (63 FR 31140). The proposed rule would 
have required repetitive inspections of the inboard and outboard flap 
actuators to measure the rotational freedom of the actuator ball screw 
adjacent to the actuator housing, and replacement of the flap actuators 
with new or serviceable actuators, if necessary. That action was 
prompted by issuance of mandatory continuing airworthiness information 
by a foreign civil airworthiness authority. The proposed actions were 
intended to prevent premature wear of the internal gears on the flap 
actuators, which could result in complete disconnection of the actuator 
gear set and a mechanical jam of the flap system. This condition could 
cause structural damage and/or significant twist of a flap panel, which 
could lead to reduced controllability of the airplane.

Actions Since Issuance of the Notice of Proposed Rulemaking (NPRM)

    Since the issuance of the NPRM on June 2, 1998, the FAA has 
received reports of six instances of jammed flap actuators on airplanes 
that were in compliance with the requirements of that proposed AD. In 
one case, a twisted flap was not detected prior to takeoff; in another 
case, a twisted flap occurred upon deployment of flaps for landing. In 
both cases, the airplanes were controllable and landed successfully. 
These reports indicate that the replacement action specified by the 
proposed rule is inadequate to address the unsafe condition.
    As a result, the FAA has reconsidered its previous position on this 
rulemaking action and issued AD 98-20-01, amendment 39-10767 (63 FR 
49661, September 17, 1998), on September 11, 1998, to address the 
unsafe condition. The actions of that AD require revising the 
procedures in the FAA-approved Airplane Flight Manual for checking the 
flap system. The amendment also requires revising the procedures in the 
FAA-approved maintenance program, and performing follow-on actions, if 
necessary. The actions specified in that AD are considered to be 
interim action until final action is identified, at which time the FAA 
may consider further rulemaking. The actions required by that AD are 
intended to prevent an unannunciated failure of the flap system due to 
a twisted outboard flap, which could result in a flap asymmetry, and 
consequent reduced controllability of the airplane.

FAA's Conclusions

    The FAA has determined that other rulemaking was required to 
address the identified unsafe condition. In light of this other on-
going rulemaking activity, the FAA hereby withdraws the proposed rule.
    Withdrawal of this NPRM constitutes only such action, and does not 
preclude the agency from issuing another notice in the future, nor does 
it commit the agency to any course of action in the future.

Regulatory Impact

    Since this action only withdraws a notice of proposed rulemaking, 
it is neither a proposed nor a final rule and therefore, is not covered 
under Executive Order 12866, the Regulatory Flexibility Act, or DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979).

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Withdrawal

    Accordingly, the notice of proposed rulemaking, Docket 98-NM-134-
AD, published in the Federal Register on June 8, 1998 (63 FR 31140), is 
withdrawn.

    Issued in Renton, Washington, on November 4, 1998.
Vi L. Lipski,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-30334 Filed 11-12-98; 8:45 am]
BILLING CODE 4910-13-U