[Federal Register Volume 64, Number 222 (Thursday, November 18, 1999)]
[Proposed Rules]
[Pages 62995-62996]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-30151]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-136-AD]
RIN 2120-AA64
Airworthiness Directives; Cessna Model 500, 501, 550, 551, and
560 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
Cessna Model 500, 501, 550, 551, and 560 series airplanes. That action
would have required revising the Airplane Flight Manual (AFM) to
include requirements for activation of the airframe pneumatic deicing
boots. Since the issuance of the NPRM, the Federal Aviation
Administration (FAA) has received new data that indicates the AFM
revision is unneccessary. Accordingly, the proposed rule is withdrawn.
FOR FURTHER INFORMATION CONTACT: Carlos Blacklock, Aerospace Engineer,
Flight Test Branch, ACE-117W, FAA, Small Airplane Directorate, Wichita
Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-
Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4166; fax
(316) 946-4407.
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 Cessna Models 500, 501, 550, 551,
and 560 series airplanes, was published in the Federal Register as a
Notice of Proposed Rulemaking (NPRM) on July 16, 1999 (64 FR 38374).
The proposed rule would have required revising the Airplane Flight
Manual (AFM) to include requirements for activation of the airframe
pneumatic deicing boots. That NPRM was prompted by reports of inflight
incidents and an accident that occurred in icing conditions where the
airframe pneumatic deicing boots were not activated. The actions
specified by that NPRM were intended to ensure that flightcrews
activate the pneumatic wing and tail deicing boots at the first signs
of ice accumulation. Such ice accumulation, if not corrected, could
result in reduced controllability of the aircraft due to adverse
aerodynamic effects of ice adhering to the airplane prior to the first
deicing cycle.
Actions That Occurred Since the NPRM Was Issued
Since the issuance of that NPRM, the manufacturer of Cessna Model
500, 501, 550, 551, and 560 series airplanes has requested that the
NPRM be withdrawn. The manufacturer contends that these models have
similar handling characteristics in icing, and that, based on the
service history and data provided to the FAA, the proposed AFM revision
for those models is unnecessary. The manufacturer concludes that the
testing summarized in its comment provides
[[Page 62996]]
evidence that the current procedures demonstrate a safe method to
operate the airplane.
The FAA concurs that the notice of proposed rulemaking for Cessna
Model 500, 501, 550, 551, and 560 series airplanes should be withdrawn
based on the following information. The manufacturer performed a
complete evaluation of the stall and handling characteristics with
simulated ice shapes on the Model 550 (Bravo) series airplanes. Stall
speeds and warning margins were evaluated with a \1/2\-inch glaze ice
shape and with a 23-minute system failure configuration. This \1/2\-
inch ice shape simulated the ice shape prior to deicing boot
activation. Maneuver margin testing consisted of left and right 40-
degree bank turns. Stall characteristics were performed with a \1/2\-
inch rime ice shape configuration. Stall characteristic testing
consisted of wings level and 30-degree bank turns. At the conclusion of
the testing it was determined that the airplane had acceptable stall
warning margin with ice shapes present. The manufacturer maintains that
the Model 500/501, Model 550/551, and Model 550 (Bravo) series
airplanes all use a common wing airfoil with some minor differences in
span and wing loading. These aircraft also use a common tail
configuration (airfoil, span, and leading edge sweep).
The Model 560 (Ultra) series airplanes underwent an extensive ice
shape stall investigation. This investigation consisted of stall
testing of the baseline airplane and the airplane with the most adverse
simulated inter-cycle ice shapes. The ice shapes consisted of \1/2\-
inch shapes on the surfaces protected by boots and 3-inch shapes on
unprotected flight surfaces. The stall speeds determined by this
testing were incorporated into the Safeflight Angle of Attack computer
to increase the stall warning margin during flight in icing conditions.
The Model 560 series airplanes angle of attack computer was also
updated to incorporate a normal mode and an ice mode stall warning
system. [The changes to the angle of attack computer on Model 560 and
560 (Ultra) series airplanes were mandated by an airworthiness
directive, Rules Docket No. 98-NM-312-AD.] Additionally, the FAA
reviewed the Type Inspection Report (TIR) for Model 550 (Bravo) series
airplane testing and found that ice shapes were placed on both the
protected and unprotected surfaces.
Therefore, the FAA concurs that the proposal should be withdrawn.
The FAA notes that the extensive testing of Model 550 series airplanes
and the similarity of Model 500 series airplanes demonstrated that
these airplanes can safely operate if the procedures for operation of
the deicing boot as specified in the applicable AFM are followed. The
FAA also notes that testing of Model 560 series airplanes revealed
problems in the stall warning margin for flight in icing conditions
that were addressed by previously issued airworthiness directives.
FAA's Conclusions
Upon further consideration, the FAA has determined that, in light
of the above information, it is unnecessary to require the proposed AFM
revision. 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-136-
AD, published in the Federal Register on July 16, 1999 (64 FR 38374),
is withdrawn.
Issued in Renton, Washington, on November 10, 1999.
John J. Hickey,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-30151 Filed 11-17-99; 8:45 am]
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