[Federal Register Volume 66, Number 195 (Tuesday, October 9, 2001)]
[Proposed Rules]
[Pages 51358-51359]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-25185]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-36-AD]
RIN 2120-AA64


Airworthiness Directives; Lockheed Model L-1011-385 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

[[Page 51359]]


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 
Lockheed Model L-1011-385 series airplanes. That action would have 
required the replacement of the flap position indicator with an 
improved flap position indicator. Since the issuance of the NPRM, the 
Federal Aviation Administration (FAA) has received new data that 
indicate that currently there are adequate annunciation provisions and 
crew procedures to safely detect and accommodate slat drive failures. 
Accordingly, the proposed rule is withdrawn.

FOR FURTHER INFORMATION CONTACT: Hector Hernandez, Aerospace Engineer, 
Systems and Flight Test Branch, ACE-116A, FAA, Atlanta Aircraft 
Certification Office, One Crown Center, 1895 Phoenix Boulevard, suite 
450, Atlanta, Georgia 30349; telephone (770) 703-6069; fax (770) 703-
6097.

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 Lockheed Model L-1011-385 series 
airplanes, was published in the Federal Register as a Notice of 
Proposed Rulemaking (NPRM) on June 17, 1998 (63 FR 33019). The proposed 
rule would have required the replacement of the flap position indicator 
with an improved flap position indicator. That action was prompted by a 
report indicating that an airplane landed at an excessive sink rate and 
sustained substantial structural damage when the leading edge slats 
failed to extend for landing and the flightcrew failed to increase 
airspeed in response, due to inadequate annunciation of the slat 
failure. The proposed actions were intended to prevent such inadequate 
annunciation, which could result in the flightcrew being unaware when 
the leading edge slats fail to extend properly; such failure could 
result in reduced stall margins, and consequent reduced controllability 
of the airplane.

Actions That Occurred Since the NPRM Was Issued

    Since the issuance of that NPRM, the FAA has received numerous 
comments from operators claiming that there are adequate annunciation 
provisions and crew procedures currently in place. The manufacturer and 
operators have identified three separate locations that show the 
position of the slats on Model L-1011 series airplanes:
    1. A slat monitor panel at the flight engineer's station displays 
the position of each of the fourteen individual slat panels by 
illuminating when each slat reaches the fully extended position, as 
determined by proximity sensors in each slat's drive mechanism. This 
slat monitor panel also displays the angular position of both the right 
and left slat drive trains on a dial-type indicator.
    2. A green ``LE EXT'' annunciation on the flap/slat position 
indicator on the center instrument panel illuminates when the slats 
reach the fully extended, 30-degree deflection.
    3. Two slat drive fault indicators indicate that the slat drive has 
been inhibited.
    Most but not all slat drive failure modes are detected and actively 
annunciated by the slat drive fault indicators. Any failure that 
inhibits the slat travel prior to full extension is clearly indicated 
on the slat monitor panel and flap/slat position indicator by the ``no 
indication of slat extension'' indicator. Current crew procedures call 
for the flight engineer to check and confirm slat extension prior to 
landing. To require the production and installation of approximately 
180 shipsets of modified indicators (to accommodate the worldwide 
fleet), which have not been manufactured in more than 15 years, does 
not is not necessary in light of the additional indications already in 
place. While the modified indicators do improve slat drive position 
awareness by actively annunciating the lack of slat extension, 
currently there are adequate annunciation provisions and crew 
procedures to safely detect and accommodate slat drive failures.

FAA's Conclusions

    Upon further consideration, the FAA has determined that mandating 
the installation of modified indicators is not necessary or justifiable 
because current annunciation provisions and crew procedures are 
adequate to address the identified unsafe condition. Accordingly, the 
proposed rule is hereby withdrawn.
    Withdrawal of this NPRM constitutes only such action, and does not 
preclude the agency from issuing another action 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-36-AD, 
published in the Federal Register on June 17, 1998 (63 FR 33019), is 
withdrawn.

    Issued in Renton, Washington, on October 2, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-25185 Filed 10-5-01; 8:45 am]
BILLING CODE 4910-13-P