[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