[Federal Register Volume 61, Number 234 (Wednesday, December 4, 1996)]
[Rules and Regulations]
[Pages 64270-64272]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-30700]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-CE-61-AD; Amendment 39-9843; AD 96-25-02]
RIN 2120-AA64
Airworthiness Directives; Mitsubishi Heavy Industries, LTD.
Models MU-2B-10, -15, -20, -25, -26, -26A, -30, -35, -36, -36A, -40,
and -60 Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment adopts a new airworthiness directive (AD) that
applies to Mitsubishi Heavy Industries, LTD. Models MU-2B-10, -15, -20,
-25, -26, -26A, -30, -35, -36, -36A, -40, and -60 airplanes. This
action requires revising the Limitations Section, the Procedures
Section, and the Master Minimum Equipment List (MMEL) of the Airplane
Flight Manual (AFM). These revisions require establishing a minimum
airspeed for sustained level flight in icing conditions, limitations
for the use of flaps for flight in icing conditions, cues for
recognizing hazardous conditions, exiting procedures in icing
conditions that are specific to Mitsubishi MU-2B series airplanes, and
ensuring the wing illumination and taxi lights are operable prior to
flight at night into known or forecast icing conditions. Several fatal
accidents, involving certain Mitsubishi MU-2B series airplanes while
flying in icing conditions, prompted this action. The actions specified
by this AD are intended to prevent operating in conditions that are
beyond the capability of the icing protection system, prevent
aerodynamic stall at higher than normal airspeed because of icing
conditions, and immediately provide the pilot with cues for recognizing
hazardous conditions and exiting these conditions, which if not
followed, could result in loss of the airplane.
DATES: Effective December 27, 1996.
Comments for inclusion in the Rules Docket must be received on or
before January 27, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Central Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket 96-CE-61-AD, Room 1558, 601 E. 12th
Street, Kansas City, Missouri 64106.
FOR FURTHER INFORMATION CONTACT: Timothy P. Smyth, Aerospace Engineer,
Small Airplane Directorate, 1201 Walnut, suite 900, Kansas City,
Missouri 64106; telephone (816) 426-6941, facsimile (816) 426-2169.
SUPPLEMENTARY INFORMATION: The FAA has received several fatal accident
reports on certain Mitsubishi MU-2B series airplanes. A common factor
in these accidents was flying into freezing rain and freezing drizzle
without recognizing specific cues and exiting these conditions.
Freezing rain and freezing drizzle (also referred to as Supercooled
Large Droplets (SLD)) are beyond the capability of the MU-2B series
airplane icing protection system. Continued operation in these
conditions will cause the airplane to develop unusual ice formations
and ice build-up in areas where the airplane does not have ice
protection. Ice accretion to this degree can cause increased drag,
increased angle of attack, and aerodynamic flow separation resulting in
uncontrollable rolling and pitching.
If the airplane is being flown by the autopilot in hazardous icing,
the increase in drag will decelerate the airplane into a stall that is
well above normal stall speed. There will not be an artificial stall
warning by stick shaker. The natural pre-stall buffet will be shorter
and stronger, or the airplane may stall with no warning. Stalling on
the autopilot can cause a spin or near vertical spiral, neither of
which may be recoverable. Using the autopilot while operating in icing
conditions could mask the cues of deceleration and the autopilot may
cross control the airplane while attempting to maintain altitude and
heading. Sideslip at stall can also be induced during the deceleration
by improper propeller pitch settings and/or engine fuel control
settings that are not in accordance with the manufacturer's
specifications.
Since an unsafe condition has been identified that is likely to
exist or develop in other Mitsubishi MU-2B series airplanes of the same
type design, this AD requires revising the Limitations Section,
Procedures Section, and the Master Minimum Equipment List (MMEL) of the
Airplane Flight Manual (AFM). These revisions require:
(1) Establishing a minimum airspeed for sustained level flight in
icing conditions,
(2) Limited use of flaps while flying in icing conditions,
(3) Recognizing cues for hazardous icing conditions specific to the
Mitsubishi Model MU-2B airplane,
(4) Operable wing illumination and taxi lights prior to flight at
night into known or forecast icing conditions, and
[[Page 64271]]
(5) Exiting procedures for icing conditions.
Since a situation exists for possible uncontrollable flight in
severe icing conditions that requires immediate adoption of this
regulation, it is found that notice and opportunity for public prior
comment hereon are impracticable, and that good cause exists for making
this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting immediate flight safety and, thus, was not
preceded by notice and opportunity to comment, comments are invited on
this rule. Interested persons are invited to comment on this rule by
submitting such written data, views, or arguments as they may desire.
Communications should identify the Rules Docket number and be submitted
in triplicate to the address specified above. All communications
received on or before the closing date for comments will be considered,
and this rule may be amended in light of the comments received. Factual
information that supports the commenter's ideas and suggestions is
extremely helpful in evaluating the effectiveness of the AD action and
determining whether additional rulemaking action would be needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the rule. All comments submitted will be
available, both before and after the closing date for comments, in the
Rules Docket for examination by interested persons. A report that
summarizes each FAA-public contact concerned with the substance of this
AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket No. 96-CE-61-AD.'' The postcard will be date stamped and
returned to the commenter.
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.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and is not a significant regulatory action under
Executive Order 12866. It has been determined further that this action
involves an emergency regulation under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979). If it is determined that
this emergency regulation otherwise would be significant under DOT
Regulatory Policies and Procedures, a final regulatory evaluation will
be prepared and placed in the Rules Docket (otherwise, an evaluation is
not required). A copy of it, if filed, may be obtained from the Rules
Docket.
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 a new airworthiness directive
(AD) to read as follows:
96-25-02 Mitsubishi Heavy Industries, Ltd.: Amendment 39-9843;
Docket No. 96-CE-61-AD.
Applicability: Models MU-2B-10, -15, -20, -25, -26, -26A, -30, -
35, -36, -36A, -40, and -60 airplanes (all serial numbers),
certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must request approval for an
alternative method of compliance in accordance with paragraph (c) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or repair on the unsafe condition
addressed by this AD; and, if the unsafe condition has not been
eliminated, the request should include specific proposed actions to
address it.
Compliance: Required as indicated in the body of this AD, unless
already accomplished.
To prevent operating in conditions that are beyond the
capability of the icing protection system, prevent aerodynamic stall
at higher than normal airspeed because of icing conditions, and
immediately provide the pilot with cues for recognizing hazardous
conditions and exiting these conditions, which if not followed,
could result in loss of the airplane, accomplish the following:
(a) Within the next 24 hours time-in-service (TIS) after the
effective date of this AD, accomplish the requirements of paragraphs
(a)(1), (a)(2), and (a)(3) of this AD. Inserting a copy of this AD
into the AFM accomplishes this action.
(1) Revise the FAA-approved Airplane Flight Manual (AFM) by
incorporating the following into the Limitations Section of the AFM.
LIMITATIONS SECTION
ICING LIMITATIONS
The minimum airspeed for sustained level flight in icing
conditions is 180 knots indicated airspeed (IAS).
Sustained flight in icing conditions with flaps extended is
prohibited except for approach and landing.
WARNING
Severe icing may result from environmental conditions outside of
those for which the airplane is designed. Flight in freezing rain,
freezing drizzle, or mixed icing conditions (supercooled liquid
water and ice crystals) may result in ice build-up on protected
surfaces exceeding the capability of the ice protection system, or
may result in ice forming aft of the protected surfaces. This ice
may not be shed using the ice protection systems, and may seriously
damage the performance and controllability of the airplane. In some
cases the ice may appear to be of relatively small proportions.
Often the appearance of the ice causing the most severe consequences
is glaze ice or a combination of glaze ice and rime ice.
During flight, severe icing conditions that exceed those for
which the airplane is certificated shall be determined by the
following visual cues. If one or more of these visual cues exist,
immediately request priority handling from Air Traffic Control to
facilitate a route or an altitude change to exit the icing
conditions.
--Airspeed losses greater than 20 knots that are not regained after
a boot de-ice cycle.
--Decrease in rate of climb during a constant airspeed climb to 300
feet per minute.
--Unusually extensive ice accreted on the airframe in areas not
normally observed to collect ice.
--Accumulation of ice on the lower surface of the wing aft of the
protected area.
--Accumulation of ice on the propeller spinner farther aft than
normally observed.
--Accumulation of ice on the upper surface of the wing aft of the
de-icing boots visible from the pilot's position that is not removed
by de-ice boot operation.
Note: Ice accretion beyond the limit of the boots on the upper
surface may be visible from the pilot's position as a solid or
partial ridge of ice.
Since the autopilot may mask tactile cues that indicate adverse
changes in handling characteristics, use of the autopilot is
prohibited when any of the visual cues
[[Page 64272]]
specified above exist, or when unusual lateral or lateral/yaw trim
requirements are encountered while the airplane is in icing
conditions.
(2) Revise the FAA-approved Airplane Flight Manual (AFM) by
incorporating the following into the Master Minimum Equipment List
(MMEL) of the AFM. Inserting a copy of this AD into the AFM
accomplishes this action.
All icing detection lights (tip tank taxi lights and wing
illumination light) must be operable prior to flight into known or
forecast icing conditions at night. [NOTE: This supersedes any
relief provided by the Master Minimum Equipment List (MMEL).]
(3) Revise the FAA-approved AFM by incorporating the following
into the Procedures Section of the AFM.
ABNORMAL PROCEDURES
SEVERE ICING ENCOUNTER
THE FOLLOWING DESCRIBES SOME OF THE WEATHER CONDITIONS THAT MAY BE
CONDUCIVE TO SEVERE IN-FLIGHT ICING:
--Visible rain at temperatures below 0 degrees Celsius ambient air
temperature.
--Droplets that splash or splatter on impact at temperatures below 0
degrees Celsius ambient air temperature.
PROCEDURES FOR EXITING SEVERE ICING ENVIRONMENT:
These procedures are applicable to all flight phases from
takeoff to landing. Monitor the ambient air temperature. While
severe icing may form at temperatures as cold as -18 degrees
Celsius, increased vigilance is warranted at temperatures around
freezing with visible moisture present. If the visual cues specified
in the Limitations Section of the AFM for identifying severe icing
conditions are observed, accomplish the following:
--Immediately request priority handling from Air Traffic Control to
facilitate a route or an altitude change to exit the severe icing
conditions to avoid extended exposure to flight conditions more
severe than those for which the airplane has been certificated.
--Avoid abrupt and excessive maneuvering that may contribute to
control difficulties.
--Do not engage the autopilot.
--If the autopilot is engaged, hold the control wheel firmly and
disengage the autopilot.
--If an unusual roll response, an uncommanded roll, or an unusual
trim is observed, lower the nose (reduce the angle of attack) and
allow the airspeed to increase before any reduction in engine power.
--Do not extend flaps during extended operation in icing conditions.
Operation with flaps extended can result in a reduced wing angle-of
-attack, with the possibility of ice forming on the upper surface
further aft of the wing than normal, possibly aft of the protected
area.
--If the flaps are extended, do not retract them until the airframe
is clear of ice.
--Report these weather conditions to Air Traffic Control.
Note 2: Operators must initiate action to notify and ensure that
flight crewmembers are apprised of this change.
(b) Incorporating the AFM revisions, as required by this AD, may
be performed by the owner/operator holding at least a private pilot
certificate as authorized by section 43.7 of the Federal Aviation
Regulations (14 CFR 43.7), and must be entered into the aircraft
records showing compliance with this AD in accordance with section
43.11 of the Federal Aviation Regulations (14 CFR 43.11).
(c) An alternative method of compliance or adjustment of the
compliance time that provides an equivalent level of safety may be
approved by the Manager, Small Airplane Directorate, Aircraft
Certification Service, 1201 Walnut, suite 900, Kansas City, Missouri
64105. The request shall be forwarded through an appropriate FAA
Maintenance Inspector, who may add comments and then send it to the
Manager, Small Airplane Directorate.
Note 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Small Airplane Directorate.
(d) Copies may be obtained and inspected at the FAA, Central
Region, Office of the Assistant Chief Counsel, Room 1558, 601 E.
12th Street, Kansas City, Missouri, or at the Office of the Federal
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(e) This amendment (39-9843) becomes effective on December 27,
1996.
Issued in Kansas City, Missouri, on November 26, 1996.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 96-30700 Filed 12-3-96; 8:45 am]
BILLING CODE 4910-13-U
