[Federal Register Volume 61, Number 19 (Monday, January 29, 1996)]
[Rules and Regulations]
[Pages 2705-2706]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-1517]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-19-AD; Amendment 39-9501; AD 96-03-04]
Airworthiness Directives; General Dynamics (Convair) Model 240
Series Airplanes, Including Model T-29 (Military) Airplanes; Model 340
and 440 Series Airplanes; and Model C-131 (Military) Airplanes;
Including Those Modified for Turbo-Propeller Power
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to various General Dynamics (Convair) airplanes, that
requires revising the Airplane Flight Manual to require that the flight
crew limit the flap settings during certain icing conditions and air
temperatures. This amendment is prompted by reports indicating that
incidents involving uncommanded pitch excursions have occurred due to
ice contaminated tailplane stall (ICTS) that occurred during or
following flight in icing conditions. If flap settings are increased
for landing when conditions for ICT S are present, elevator control
could be affected adversely and the airplane could descend
uncontrollably. The actions specified by this AD are intended to ensure
that the flight crew is advised of the potential hazard related to
increasing the flap settings when conditions for ICTS are present, and
the procedures necessary to address it.
EFFECTIVE DATE: February 28, 1996.
ADDRESSES: Information pertaining to this rulemaking action may be
examined at the Federal Aviation Administration (FAA), Transport
Airplane Directorate, Rules Docket, 1601 Lind Avenue SW., Renton,
Washington; or at the FAA, Los Angeles Aircraft Certification Office,
Transport Airplane Directorate, 3960 Paramount Boulevard, Lakewood,
California.
FOR FURTHER INFORMATION CONTACT: Andrew Gfrerer, Aerospace Engineer,
Systems and Equipment Branch, ANM-130L, FAA, Transport Airplane
Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount
Boulevard, Lakewood, California 90712; telephone (310) 627-5338; fax
(310) 627-5210.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to various General Dynamics (Convair)
airplanes was published in the Federal Register on June 16, 1995 (60 FR
31648). That action proposed to require revising the FAA-approved
Airplane Flight Manual (AFM) to require that the flight crew limit the
flap settings during certain icing conditions and air temperatures.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
One commenter supports the proposed rule.
One commenter supports the proposed rule, but believes that an
allowance should be made for using a setting of greater than flaps 30
after icing conditions have been encountered if outside air
temperatures in the landing area are well above freezing. The commenter
indicates that icing conditions may be encountered at cruising
altitudes, but the ground temperatures could be much warmer. The
commenter believes that there is virtually no chance that ice would
remain on the tail. From the commenter's experience, all ice that has
collected on the wing leading edges, engine nacelles, windscreens, and
windshield wipers will have disappeared by the time the indicating
outside air temperature has reached +5 degrees Celsius on descent.
In light of these remarks, the commenter suggests that the AFM
revision required by paragraph (a) of the proposed rule be reworded as
follows:-
``Flap selection is limited to a maximum of 30 degrees after icing
conditions have been encountered if the indicated OAT on approach is +5
degrees Celsius or lower; or if icing conditions are anticipated during
approach and landing; or when the outside air temperature is +5 degrees
Celsius or below and any visible moisture is present.''
The FAA does not concur with the commenter's suggestion. Operators
cannot generally assume that accreted ice will not be present on wings
and tailplanes if the outside air temperatures are above +5 degrees
Celsius on approach. Ice sublimation, melting, and shedding are not
only functions of temperature, but also are dependent upon other
factors such as the nature, size, and extent of ice accretion;
operation of ice protection systems; time of flight in temperatures
above freezing; and airplane speed.
The commenter's concern regarding incurring a flap extension
limitation after encountering, and then departing, icing conditions has
merit. However, the airplane must be free of ice before the flaps are
extended to greater than 30 degrees. Since ice can accrete on
tailplanes with a small leading edge radius when there is no evidence
of ice accretion on the wings, a method of visual inspection of the
wings, tailplanes, and/or proven ice detectors or ice evidence probes
would be necessary to assure clean surfaces.
One commenter requests that the proposed AD be withdrawn. The
commenter states that the airplane can be operated quite safely within
the environment to which it is certified when the anti-icing system is
operational and functioning, and when that system is used in the manner
in which it was intended.-
The FAA does not concur with the commenter's request. Test pilots
of Convair Model 5800 series airplanes actually experienced evidence of
ice contaminated tailplane stall (ICTS) during pushover maneuver flight
tests. (Model 5800 series airplanes are similar to Model 340 series
airplanes equipped with turbo-prop engines.) For this reason the type
certificate holder agreed with the FAA that a flap extension
restriction during operation in icing conditions is necessary. The
specific flight test used to determine susceptibility to ICTS is a
pushover maneuver to generate an increased angle of attack on the
horizontal tailplane. This maneuver is performed with ice shapes on the
tailplane and flaps in approach and landing positions, at speeds from
near approach to maximum for the configurations. The test procedure
requires a push force throughout the maneuver to zero load factor. A
force reversal would be indicative of an elevator hinge moment reversal
caused by airflow separation due to accreted ice and an increased angle
of attack due to pitch rate, and would define the aircraft as
susceptible to ICTS. Because all affected Convair airplane models have
tailplane designs that are similar to the model tested, this AD
requires a flap limitation.-
The FAA has revised this final rule to clarify that the unsafe
condition
[[Page 2706]]
specified in this AD can occur if the flap settings are increased when
conditions for ICTS are present.
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule as proposed.
There are approximately 282 Model 240 series airplanes, including
Model T-29 (military) airplanes; Model 340 and 440 series airplanes;
Model C-131 (military) airplanes, and those models modified for turbo-
propeller power; of the affected design in the worldwide fleet. The FAA
estimates that 197 airplanes of U.S. registry will be affected by this
AD, that it will take approximately 1 work hour per airplane to
accomplish the required actions, and that the average labor rate is $60
per work hour. Based on these figures, the cost impact of the AD on
U.S. operators is estimated to be $11,820, or $60 per airplane.-
The cost impact figure discussed above is based on assumptions that
no operator has yet accomplished any of the requirements of this AD
action, and that no operator would accomplish those actions in the
future if this AD were not adopted.
The regulations adopted herein will not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this action (1) is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a
significant economic impact, positive or negative, on a substantial
number of small entities under the criteria of the Regulatory
Flexibility Act. A final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it may be obtained
from the Rules Docket at the location provided under the caption
ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES -
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
96-03-04 General Dynamics (Convair): Amendment 39-9501. Docket 95-
NM-19-AD.
Applicability: All Model 240 series airplanes, including Model
T-29 (military) airplanes; Model 340 and 440 series airplanes; and
Model C-131 (military) airplanes; including those models modified
for turbo-propeller power (commonly referred to as Model 580, 600,
and 640 series airplanes); certificated in any category.
Compliance: Required as indicated, unless accomplished
previously.
To ensure that the flight crew is advised of the potential
hazard associated with increasing the flap settings when ice
contaminated tailplane stall (ICTS) conditions are present, and the
procedures necessary to address it, accomplish the following:
(a) Within 30 days after the effective date of this AD, revise
the Limitations Section of the FAA-approved Airplane Flight Manual
(AFM) to include the following procedures, which will limit the flap
settings during certain icing conditions and air temperatures. This
may be accomplished by inserting a copy of this AD in the AFM.
``FLAP LIMITATION IN ICING CONDITIONS
Flap selection is limited to a maximum of 30 degrees after icing
conditions have been encountered; or when icing conditions are
anticipated during approach and landing; or when the outside air
temperature is +5 degrees Celsius or below and any visible moisture
is present.''
(b) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Los Angeles Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Los Angeles ACO.
Note: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Los Angeles ACO.
(c) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
(d) This amendment becomes effective on February 28, 1996.
Issued in Renton, Washington, on January 23, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-1517 Filed 1-26-96; 8:45 am]
BILLING CODE 4910-13-U
