[Federal Register Volume 64, Number 197 (Wednesday, October 13, 1999)]
[Proposed Rules]
[Pages 55440-55441]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-26714]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-131-AD]
RIN 2120-AA64


Airworthiness Directives; Saab Model SAAB SF-340 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 Saab 
Model SAAB SF-340 series airplanes. That action would have required 
replacement of the existing pneumatic de-icing boot pressure indicator 
switch with a newly designed switch. Since the issuance of the NPRM, 
the Federal Aviation Administration (FAA) has received new data that 
demonstrates that the unsafe condition cannot occur. Accordingly, the 
proposed rule is withdrawn.

FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2110; fax (425) 227-1149.

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 Saab Model SAAB SF-340 series airplanes, 
was published in the Federal Register as a Notice of Proposed 
Rulemaking (NPRM) on July 22, 1999 (64 FR 39450). The proposed rule 
would have required replacement of the existing pneumatic de-icing boot 
pressure indicator switch with a newly designed switch. That action was 
prompted by an occurrence on a similar airplane model in which the 
pneumatic de-icing boot indication light may have provided the 
flightcrew with misleading information as to the proper functioning

[[Page 55441]]

of the de-icing boots. The proposed actions were intended to prevent 
ice accumulation on the airplane leading edges, which could reduce 
controllability of the airplane.

Actions That Occurred Since the NPRM Was Issued

    Since the issuance of that NPRM, the manufacturer has provided the 
Federal Aviation Administration (FAA) with test and analytical data 
that substantiate that Saab Model SAAB SF-340 series airplanes feature 
a pneumatic boot de-icing system that assures the proper pneumatic 
threshold has been reached for effective pneumatic de-ice boot 
operation prior to illuminating the indication light. The FAA concludes 
that the de-icing boot design on Saab Model SAAB SF-340 series 
airplanes includes sufficient robust features to preclude the unsafe 
condition addressed in the NPRM.

FAA's Conclusions

    Upon further consideration, the FAA has determined that the 
proposed actions of the NPRM (Docket 99-NM-131-AD) are unnecessary 
because the identified unsafe condition does not exist on Saab Model 
SAAB SF-340 series airplanes. Accordingly, the proposed rule is hereby 
withdrawn.
    Withdrawal of this notice of proposed rulemaking 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 99-NM-131-
AD, published in the Federal Register on July 22 (64 FR 39450), is 
withdrawn.

    Issued in Renton, Washington, on October 6, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-26714 Filed 10-12-99; 8:45 am]
BILLING CODE 4910-13-P