[Federal Register Volume 64, Number 222 (Thursday, November 18, 1999)]
[Proposed Rules]
[Pages 62990-62991]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-30148]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-146-AD]
RIN 2120-AA64
Airworthiness Directives; British Aerospace Jetstream Model 4101
Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Proposed rule; withdrawal.
-----------------------------------------------------------------------
SUMMARY: This action withdraws a notice of proposed rulemaking (NPRM)
that proposed a new airworthiness directive (AD), applicable to certain
British Aerospace Jetstream Model 4101 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 that the specified AFM
revision is not necessary. Accordingly, the proposed rule is withdrawn.
FOR FURTHER INFORMATION CONTACT: Norman 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 certain British Aerospace Jetstream Model
4101 airplanes, was published in the Federal Register as a Notice of
Proposed Rulemaking (NPRM) on July 16, 1999 (64 FR 38335). The proposed
rule would have required revising the Airplane Flight Manual (AFM) to
include requirements for activation of the airframe pneumatic deicing
boots. That action 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 action specified by the proposed
AD was 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 British
Aerospace Jetstream Model 4101 airplanes has requested that the NPRM be
withdrawn. The manufacturer advises that, based on the service history
and data provided to the FAA, the proposed AFM revision for those
models is unnecessary.
The FAA concurs that the notice of proposed rulemaking for British
Aerospace Jetstream Model 4101 airplanes should be withdrawn based on
the following information. British Aerospace submitted a summary of the
handling and performance flight test results that were produced during
the original flight in icing certification, and referenced the data
summary in response to the proposed rulemaking. The FAA requested and
subsequently received copies of the full handling and performance
flight test results for certification in the icing conditions specified
in Appendix C of part 25 of the Federal Aviation Regulations (14 CFR
25), and the draft issue of AMJ25.1419, which was used as guidance for
compliance with JAR/FAR 25.1419. The FAA reviewed these reports and
guidance material and finds that the Jetstream 4101 airplane was
adequately tested with a variety of natural ice accretions on both the
protected and unprotected surfaces. Handling and performance flight
test was accomplished for the following: Normal Operation of the
Deicing Boots, \1/2\-to \3/4\-inch of ice on the protected wing leading
edges and up to 3 inches of ice on unprotected leading edges; Simulated
Failure of the Deicing Boots, approximately 1-to 1\1/2\-inches of ice
on all leading edges; and Ice Accreted During the Take-off Phase, a
thin rough layer of ice accreted during the initial take-off phase to
400 feet, prior to operation of deicing boots.
These ice accretion depths are consistent with the operational
procedure of the airframe deicing system, and were established to
address the following: Ice accreted during the rest time of a deicing
cycle, delayed operation or failure of the system, and residual ice
accumulations. The flight testing examined stall speeds, stall warning
margins, stall characteristics, maneuver margins, longitudinal
controllability, flap configuration changes, ability to trim,
susceptibility to tailplane stall, and longitudinal, lateral, and
directional stability. The angles of attack for activation of the stall
warning system and stall identification system (i.e., stick shaker or
stick pusher) are reset to lower values (i.e., higher speeds) for
flight in icing and safe flight speeds (minimum operating speeds)
established accordingly. Affected AFM performance information was
derived for icing conditions based on the higher operating speeds, in
accordance with JAA draft AMJ25.1419.
FAA's Conclusions
Upon further consideration, the FAA has determined that, in light
of the above information, it is unnecessary to require the AFM revision
as proposed. 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.
[[Page 62991]]
The Withdrawal
Accordingly, the notice of proposed rulemaking, Docket 99-NM-146-
AD, published in the Federal Register on July 16, 1999 (64 FR 38335),
is withdrawn.
Issued in Renton, Washington, on November 10, 1999.
John J. Hickey,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-30148 Filed 11-17-99; 8:45 am]
BILLING CODE 4910-13-P
