[Federal Register Volume 60, Number 2 (Wednesday, January 4, 1995)]
[Proposed Rules]
[Page 388]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-61]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-155-AD]


Airworthiness Directives; Canadair 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 
Canadair Model CL-600-2B19 series airplanes. That action would have 
required removal of certain shear pins and installation of stronger 
shear pins on the elevator flutter dampers. The proposed actions were 
intended to prevent problems associated with undampened vibration of 
the elevators in normal cruise conditions. Since the issuance of the 
NPRM, the Federal Aviation Administration (FAA) has issued other 
rulemaking that positively addresses the identified unsafe condition. 
Accordingly, the proposed rule is withdrawn.

FOR FURTHER INFORMATION CONTACT: Franco Pieri, Aerospace Engineer, 
Airframe Branch, ANE-172, New York Aircraft Certification Office, FAA, 
Engine and Propeller Directorate, 181 South Franklin Avenue, Room 202, 
Valley Stream, New York 11581; telephone (516) 791-6220; fax (516) 791-
9024.

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 Canadair Model CL-600-2B19 series 
airplanes, was published as a Notice of Proposed Rulemaking (NPRM) in 
the Federal Register on October 11, 1994 (59 FR 51392). The proposed 
rule would have required removal of certain shear pins from the 
elevator flutter dampers, and installation of stronger shear pins. That 
action was originally prompted by a report of sheared-off shear pins 
found on one airplane's elevator dampers. The proposed actions were 
intended to prevent undampened vibration of the elevators in normal 
cruise conditions, resulting from the failure of the shear pins 
installed in the elevator flutter dampers; when combined with hydraulic 
system failures, this condition can result in reduced controllability 
of the airplane. -
    Since the issuance of that NPRM, Transport Canada Aviation, which 
is the airworthiness authority for Canada, has notified the FAA that 
the lugs of the elevator flutter damper sheared off of two Model CL-
600-2B19 series airplanes. Investigation revealed that the shear pins 
that were installed in the elevator flutter dampers on these incident 
airplanes were the stronger pins, whose installation would have been 
required by the NPRM. The stronger shear pins caused the loads to 
transfer to the lugs of the elevator flutter damper, which subsequently 
failed under the increased loads. -
    Consequently, on November 17, 1994, the FAA issued AD 94-24-02, 
amendment 39-9075 (59 FR 60888, November 29, 1994), applicable to 
certain Canadair Model CL-600-2B19 series airplanes, to require the 
removal of all elevator flutter dampers. It also requires revisions to 
the FAA-approved Airplane Flight Manual (AFM) that advise the flight 
crew of the need to perform daily checks to verify proper operation of 
the elevator control system, and that restrict altitude and airspeed of 
the airplane. -
    The FAA has determined that the actions currently required by AD 
94-24-02 positively address the previously identified unsafe condition. 
Removal of the elevator flutter dampers from these airplanes and the 
daily checks of the elevator control system will ensure that the risk 
of jamming or restricting movement of the elevator is eliminated. 
Additionally, the operational limitation will enable the pilot to avert 
conditions of potential flutter. -
    In light of the fact that other rulemaking adequately addresses the 
identified unsafe condition, the FAA finds that the previously proposed 
action is unwarranted and hereby withdraws the NPRM.-
    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.-
    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 94-NM-155-
AD, published in the Federal Register on October 11, 1994 (59 FR 
51392), is withdrawn.

    Issued in Renton, Washington, on December 28, 1994.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-61 Filed 1-3-95; 8:45 am]
BILLING CODE 4910-13-U