[Federal Register Volume 63, Number 32 (Wednesday, February 18, 1998)]
[Rules and Regulations]
[Pages 8074-8078]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-3695]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-174-AD; Amendment 39-10346; AD 98-04-34]
RIN 2120-AA64


Airworthiness Directives; Mitsubishi Model YS-11 and YS-11A 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to all Mitsubishi Model YS-11 and YS-11A series airplanes, 
that requires revising the Airplane Flight Manual (AFM) to specify 
procedures that will prohibit flight in severe icing conditions (as 
determined by certain visual cues), limit or prohibit the use of 
various flight control devices while in severe icing conditions, and 
provide the flight crew with recognition cues for, and procedures for 
exiting from, severe icing conditions. This amendment is prompted by 
results of a review of the requirements for certification of the 
airplane in icing conditions, new information on the icing environment, 
and icing data provided currently to the flight crews. The actions 
specified by this AD are intended to minimize the potential hazards 
associated with operating the airplane in severe icing conditions by 
providing more clearly defined procedures and limitations associated 
with such conditions.

EFFECTIVE DATE: March 25, 1998.

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, Transport Airplane Directorate, Los Angeles 
Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, 
California.

FOR FURTHER INFORMATION CONTACT: Alan Sinclair, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130L, FAA, Transport Airplane 
Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount 
Boulevard, Lakewood, California 90712; telephone (562) 627-5338; fax 
(562) 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 Mitsubishi Model YS-11 and YS-11A 
series airplanes was published in the Federal Register on September 16, 
1997 (62 FR 48567). That action proposed to require the Limitations 
Section of the FAA-approved AFM to specify procedures that would:
     Require flight crews to immediately request priority 
handling from Air Traffic Control to exit severe icing conditions (as 
determined by certain visual cues);
     Prohibit flight in severe icing conditions (as determined 
by certain visual cues);
     Prohibit use of the autopilot when ice is formed aft of 
the protected surfaces of the wing, or when an unusual lateral trim 
condition exists; and
     Require that all icing wing inspection lights be operative 
prior to flight into known or forecast icing conditions at night.
    That action also proposed to require revising the Normal Procedures 
Section of the FAA-approved AFM to specify procedures that would:
     Limit the use of the flaps and prohibit the use of the 
autopilot when ice is observed forming aft of the protected surfaces of 
the wing, or if unusual lateral trim requirements or autopilot trim 
warnings are encountered; and
     Provide the flight crew with recognition cues for, and 
procedures for exiting from, severe icing conditions.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the following comments received.
    In addition to the proposed rule described previously, in September 
1997, the FAA issued 24 other similar proposals that address the 
subject unsafe condition on various airplane models (see below for a 
listing of all 24 proposed rules). These 24 proposals also were 
published in the Federal Register on September 16, 1997. This final 
rule contains the FAA's responses to all relevant public comments 
received for each of these proposed rules.

------------------------------------------------------------------------
                            Manufacturer/airplane     Federal Register  
        Docket No.                  model                 citation      
------------------------------------------------------------------------
97-CE-49-AD...............  Aerospace              62 FR 48520          
                             Technologies of                            
                             Australia, Models                          
                             N22B and N24A.                             
97-CE-50-AD...............  Harbin Aircraft Mfg.   62 FR 48513          
                             Corporation, Model                         
                             Y12 IV.                                    
97-CE-51-AD...............  Partenavia             62 FR 48524          
                             Costruzioni                                
                             Aeronauticas,                              
                             S.p.A., Models P68,                        
                             AP68TP 300, AP68TP                         
                             600.                                       
97-CE-52-AD...............  Industrie              62 FR 48502          
                             Aeronautiche                               
                             Meccaniche Rinaldo                         
                             Piaggio S.p.A.,                            
                             Model P-180.                               
97-CE-53-AD...............  Pilatus Aircraft       62 FR 48499          
                             Ltd., Models PC-12                         
                             and PC-12/45.                              
97-CE-54-AD...............  Pilatus Britten-       62 FR 48538          
                             Norman Ltd., Models                        
                             BN-2A, BN-2B, and BN-                      
                             2T.                                        
97-CE-55-AD...............  SOCATA--Groupe         62 FR 48506          
                             Aerospatiale, Model                        
                             TBM-700.                                   
97-CE-56-AD...............  Aerostar Aircraft      62 FR 48481          
                             Corporation, Models                        
                             PA-60-600, -601, -                         
                             601P, -602P, and -                         
                             700P.                                      
97-CE-57-AD...............  Twin Commander         62 FR 48549          
                             Aircraft                                   
                             Corporation, Models                        
                             500, -500-A, -500-B,-                      
                             500-S, -500-U, -520,                       
                             -560, -560-A, -560-                        
                             E, -560-F, -680, -                         
                             680-E, -680FL(P), -                        
                             680T, -680V, -680W, -                      
                             681, -685, -690, -                         
                             690A, -690B, -690C, -                      
                             690D, -695, -695A, -                       
                             695B, and 720.                             
97-CE-58-AD...............  Raytheon Aircraft      62 FR 48517          
                             Company (formerly                          
                             known as Beech                             
                             Aircraft                                   
                             Corporation), Models                       
                             E55, E55A, 58, 58A,                        
                             58P, 58PA, 58TC,                           
                             58TCA, 60 series, 65-                      
                             B80 series, 65-B-90                        
                             series, 90 series,                         
                             F90 series, 100                            
                             series, 300 series,                        
                             and B300 series.                           
97-CE-59-AD...............  Raytheon Aircraft      62 FR 48531          
                             Company (formerly                          
                             known as Beech                             
                             Aircraft                                   
                             Corporation), Model                        
                             2000.                                      
97-CE-60-AD...............  The New Piper          62 FR 48542          
                             Aircraft, Inc.,                            
                             Models PA-46-310P                          
                             and PA-46-350P.                            

[[Page 8075]]

                                                                        
97-CE-61-AD...............  The New Piper          62 FR 52294          
                             Aircraft, Inc.,                            
                             Models PA-23, PA-23-                       
                             160, PA-23-235, PA-                        
                             23-250, PA-E23-250,                        
                             PA-30, PA-39, PA-40,                       
                             PA-31, PA-31-300, PA-                      
                             31-325, PA-31-350,                         
                             PA-34-200, PA-34-                          
                             200T, PA-34-220T, PA-                      
                             42, PA-42-720, PA-42-                      
                             1000.                                      
97-CE-62-AD...............  Cessna Aircraft        62 FR 48535          
                             Company, Models                            
                             P210N, T210N, P210R,                       
                             and 337 series.                            
97-CE-63-AD...............  Cessna Aircraft        62 FR 48528          
                             Company, Models                            
                             T303, 310R, T310R,                         
                             335, 340A, 402B,                           
                             402C, 404, F406,                           
                             414, 414A, 421B,                           
                             421C, 425, and 441.                        
97-CE-64-AD...............  SIAI-Marchetti S.r.I.  62 FR 48510          
                             (Augusta), Models                          
                             SF600 and SF600A.                          
97-NM-170-AD..............  Cessna Aircraft        62 FR 48560          
                             Company, Models 500,                       
                             501, 550, 551, and                         
                             560 series.                                
97-NM-171-AD..............  Sabreliner             62 FR 48556          
                             Corporation, Models                        
                             40, 60, 70, and 80                         
                             series.                                    
97-NM-172-AD..............  Gulfstream Aerospace,  62 FR 48563          
                             Model G-159 series.                        
97-NM-173-AD..............  McDonnell Douglas,     62 FR 48553          
                             Models DC-3 and DC-4                       
                             series.                                    
97-NM-174-AD..............  Mitsubishi Heavy       62 FR 48567          
                             Industries, Model YS-                      
                             11 and YS-11A series.                      
97-NM-175-AD..............  Frakes Aviation,       62 FR 48577          
                             Model G-73 (Mallard)                       
                             and G-73T series.                          
97-NM-176-AD..............  Lockheed, Model L-14   62 FR 48574          
                             and L-18 series.                           
97-NM-177-AD..............  Fairchild, Models F27  62 FR 48570          
                             and FH227 series.                          
------------------------------------------------------------------------

Comment 1. Removal of Certain Visual Cues

    One commenter, the manufacturer, requests that the sentence 
describing visual cues of ``Accumulation of ice on the engine nacelles 
and propeller spinners farther aft than normally observed'' in 
paragraph (a) of the proposal be deleted. The manufacturer bases this 
request on the fact that ice will not accrete to the propeller spinner 
because the heater element for anti-icing is installed in the spinner. 
Further, the manufacturer points out that it is impossible to see the 
engine nacelle from the cockpit.
    The FAA concurs, and has revised the final rule by removing that 
specific visual cue from the visual cue requirements specified in the 
final rule.

Comment 2. Unsubstantiated Unsafe Condition for This Model

    One commenter suggests that the AD's were developed in response to 
a suspected contributing factor of an accident involving an airplane 
type unrelated to the airplanes specified in the proposal. The 
commenter states that these proposals do not justify that an unsafe 
condition exists or could develop in a product of the same type design 
specified in the proposal. Therefore, the commenter asserts that the 
proposal does not meet the criteria for the issuance of an AD as 
specified in the Federal Aviation Regulations (14 CFR part 39 ).
    The FAA does not concur. As stated in the Notice of Proposed 
Rulemaking (NPRM), the FAA has identified an unsafe condition 
associated with operating the airplane in severe icing conditions. As 
stated in the preamble to the proposal, the FAA has not required that 
airplanes be shown to be capable of operating safely in icing 
conditions outside the certification envelope specified in Appendix C 
of part 25 of the Federal Aviation Regulations (14 CFR part 25). This 
means that any time an airplane is flown in icing conditions for which 
it is not certificated, there is a potential for an unsafe condition to 
exist or develop and the flight crew must take steps to exit those 
conditions expeditiously. Further, the FAA has determined that flight 
crews are not currently provided with information necessary to 
determine when an airplane is operating in icing conditions for which 
it is not certificated or what action to take when such conditions are 
encountered. The absence of this information presents an unsafe 
condition because, without that information, a pilot may remain in 
potentially hazardous icing conditions. This AD addresses the unsafe 
condition by requiring AFM revisions that provide the flight crews with 
visual cues to determine when icing conditions have been encountered 
for which the airplane is not certificated, and that provide procedures 
to safely exit those conditions.
    Further, in the preamble of the proposed rule, the FAA discussed 
the investigation of roll control anomalies and explained that the 
investigation was not a complete certification program. The testing was 
designed to examine only the roll handling characteristics of the 
airplane in certain droplets the size of freezing drizzle. The testing 
was not a certification test to approve the airplane for flight into 
freezing drizzle. The results of the tests were not used to determine 
if this AD is necessary, but rather to determine if design changes were 
needed to prevent a catastrophic roll upset. The roll control testing 
and the AD are two unrelated actions.
    Additionally, in the preamble of the proposed rule, the FAA 
acknowledged that the flight crew of any airplane that is certificated 
for flight icing conditions may not have adequate information 
concerning flight in icing conditions outside the icing envelope. 
However, in 1996, the FAA found that the specified unsafe condition 
must be addressed as a higher priority on airplanes equipped with 
pneumatic deicing boots and unpowered roll control systems. These 
airplanes were addressed first because the flight crew of an airplane 
having an unpowered roll control system must rely solely on physical 
strength to counteract roll control anomalies, whereas a roll control 
anomaly that occurs on an airplane having a powered roll control system 
need not be offset directly by the flight crew. The FAA also placed a 
priority on airplanes that are used in regularly scheduled passenger 
service. The FAA has previously issued AD's to address those airplanes. 
Since the issuance of those AD's, the FAA has determined that similar 
AD's should be issued for similarly equipped airplanes that are not 
used in regularly scheduled passenger service.

Comment 3. AD Is Inappropriate To Address Improper Operation of the 
Airplane

    One commenter requests that the proposed AD be withdrawn because an 
unsafe condition does not exist within the airplane. Rather, the 
commenter asserts that the unsafe condition is the improper operation 
of the airplane. The commenter further asserts that issuance of an AD 
is an inappropriate method to address improper operation of the 
airplane.
    The FAA does not concur. The FAA has determined that an unsafe 
condition does exist as explained in the proposed notice and discussed 
previously. As specifically addressed in Amendment 39-106 of part 39 of 
the Federal Aviation Regulations (14 CFR part 39), the responsibilities 
placed on the FAA statute (49 U.S.C., formerly the Federal Aviation 
Act), justify allowing AD's to be issued for unsafe conditions however 
and wherever found, regardless of

[[Page 8076]]

whether the unsafe condition results from maintenance, design defect, 
or any other reason.
    This same commenter considers that part 91 (rather than part 39) of 
the Federal Aviation Regulations (14 CFR part 91) is the appropriate 
regulation to address the problems of icing encountered outside of the 
limits for which the airplane is certificated. Therefore, the commenter 
requests that the FAA withdraw the proposal.
    The FAA does not concur. Service experience demonstrates that 
flight in icing conditions that are outside the icing certification 
envelope does occur. Apart from the visual cues provided in these final 
rules, there is no existing method provided to the flight crews to 
identify when the airplane is in a condition that exceeds the icing 
certification envelope. Because this lack of awareness may create an 
unsafe condition, the FAA has determined that it is appropriate to 
issue an AD to require revision of the AFM to provide this information.
    One commenter asserts that, while it is prudent to advise and 
routinely remind the pilots about the hazards associated with flight 
into known or forecast icing conditions, the commenter is opposed to 
the use of an AD to accomplish that function. The commenter states that 
pilots' initial and bi-annual flight checks are the appropriate 
vehicles for advising the pilots of such hazards, and that such 
information should be integrated into the training syllabus for all 
pilot training.
    The FAA does not concur that substituting advisory material and 
mandatory training for issuance of an AD is appropriate. The FAA 
acknowledges that, in addition to the issuance of an AD, information 
specified in the revision to the AFM should be integrated into the 
pilot training syllabus. However, the development and use of such 
advisory materials and training alone are not adequate to address the 
unsafe condition. The only method of ensuring that certain information 
is available to the pilot is through incorporation of the information 
into the Limitations Section of the AFM. The appropriate vehicle for 
requiring such revision of the AFM is issuance of an AD. No change is 
necessary to the final rule.

Comment 4. Inadequate Visual Cues

    One commenter provides qualified support for the AD. The commenter 
notes that the recent proposals are identical to the AD's issued about 
a year ago. Although the commenter supports the intent of the AD's as 
being appropriate and necessary, the commenter states that it is 
unfortunate that the flight crew is burdened with recognizing icing 
conditions with visual cues that are inadequate to determine certain 
icing conditions. The commenter points out that, for instance, side 
window icing (a very specific visual cue) was determined to be a valid 
visual cue during a series of icing tanker tests on a specific 
airplane; however, later testing of other models of turboprop airplanes 
revealed that side window icing was invalid as a visual cue for 
identifying icing conditions outside the scope of Appendix C.
    The FAA does not concur with the commenters' request to provide 
more specific visual cues. The FAA finds that the value of visual cues 
has been substantiated during in-service experience. Additionally, the 
FAA finds that the combined use of the generic cues provided and the 
effect of the final rules in increasing the awareness of pilots 
concerning the hazard of operating outside of the certification icing 
envelope will provide an acceptable level of safety. Although all of 
the cues may not be exhibited on a particular model, the FAA considers 
that at least some of the cues will be exhibited on all of the models 
affected by this AD. For example, some airplanes may not have side 
window cues in freezing drizzle, but would exhibit other cues (such as 
accumulation of ice aft of the protected area) under those conditions. 
Other than the previously discussed removal of a visual cue that 
referenced ice on the engine nacelles and propeller spinners, the FAA 
considers that no other changes regarding visual cues are necessary to 
the final rule. However, for those operators that elect to identify 
airplane-specific visual cues, the FAA would consider a request for 
approval of an alternative method of compliance, in accordance with the 
provisions of this AD.

Comment 5. Request for Research and Use of Wing-Mounted Ice Detectors

    One commenter requests that wing-mounted ice detectors, which 
provide real-time icing severity information (or immediate feedback) to 
flight crews, continue to be researched and used throughout the fleet. 
The FAA infers from this commenter's request that the commenter asks 
that installation of these ice detectors be mandated by the FAA.
    While the FAA supports the development of such ice detectors, the 
FAA does not concur that installation of these ice detectors should be 
required at this time. Visual cues are adequate to provide an 
acceptable level of safety; therefore, mandatory installation of ice 
detector systems, in this case, is not necessary to address the unsafe 
condition. Nevertheless, because such systems may improve the current 
level of safety, the FAA has officially tasked the Aviation Rulemaking 
Advisory Committee (ARAC) to develop a recommendation concerning ice 
detection. Once the ARAC has submitted its recommendation, the FAA may 
consider further rulemaking action to require installation of such 
equipment.

Comment 6. Particular Types of Icing

    This same commenter also requests that additional information be 
included in paragraph (a) of the AD that would specify particular types 
of icing or particular accretions that result from operating in 
freezing precipitation. The commenter asserts that this information is 
of significant value to the flight crew.
    The FAA does not concur with the commenter's suggestion to specify 
types of icing or accretion. The FAA has determined that supercooled 
large droplets (SLD) can result in rime ice, mixed (intermediate) ice, 
and ice with glaze or clear appearance. Therefore, the FAA finds that 
no type of icing can be excluded from consideration during operations 
in freezing precipitation, and considers it unnecessary to cite those 
types of icing in the AD.

Conclusion

    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 with the change previously 
described. The FAA has determined that this change will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 76 Mitsubishi Model YS-11 and YS-11A-200, -
300, -500, and -600 series airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 38 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 $2,280, 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

[[Page 8077]]

that no operator would accomplish those actions in the future if this 
AD were not adopted.
    In addition, the FAA recognizes that the required actions may 
impose operational costs. However, these costs are incalculable because 
the frequency of occurrence of the specified conditions and the 
associated additional flight time cannot be determined. Nevertheless, 
because of the severity of the unsafe condition, the FAA has determined 
that continued operational safety necessitates the imposition of the 
costs.

Regulatory Impact

    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:

98-04-34  Mitsubishi Heavy Industries, Ltd. [Formerly Nihon 
Aeroplane Manufacturing Company (NMAC)]: Amendment 39-10346. Docket 
97-NM-174-AD.

    Applicability: All Model YS-11 and YS-11A-200, -300, -500, and -
600 series airplanes, 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 (b) 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, unless accomplished 
previously.
    To minimize the potential hazards associated with operating the 
airplane in severe icing conditions by providing more clearly 
defined procedures and limitations associated with such conditions, 
accomplish the following:
    (a) Within 30 days after the effective date of this AD, 
accomplish the requirements of paragraphs (a)(1) and (a)(2) of this 
AD.

    Note 2: Operators should initiate action to notify and ensure 
that flight crewmembers are apprised of this change.

    (1) Revise the FAA-approved Airplane Flight Manual (AFM) by 
incorporating the following into the Limitations Section of the AFM. 
This may be accomplished by inserting a copy of this AD in the AFM.

``Warning

    Severe icing may result from environmental conditions outside of 
those for which the airplane is certificated. 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 degrade the performance and controllability of the 
airplane.
     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.

--Unusually extensive ice accumulation on the airframe and 
windshield in areas not normally observed to collect ice.
--Accumulation of ice on the upper surface of the wing aft of the 
protected area.

     Since the autopilot, when installed and operating, may 
mask tactile cues that indicate adverse changes in handling 
characteristics, use of the autopilot is prohibited when any of the 
visual cues specified above exist, or when unusual lateral trim 
requirements or autopilot trim warnings are encountered while the 
airplane is in icing conditions.
     All wing icing inspection lights must be operative 
prior to flight into known or forecast icing conditions at night.

     [Note: This supersedes any relief provided by the Master 
Minimum Equipment List (MMEL).]''

    (2) Revise the FAA-approved AFM by incorporating the following 
into the Normal Procedures Section of the AFM. This may be 
accomplished by inserting a copy of this AD into the AFM.

``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 the 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 in order 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 
exacerbate 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 or uncommanded roll control 
movement is observed, reduce the angle-of-attack.
     Do not extend flaps when holding 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 on 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.''
    (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. The

[[Page 8078]]

request shall be forwarded through an appropriate FAA Operations 
Inspector, who may add comments and then send it to the Manager, Los 
Angeles ACO.

    Note 3: 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 March 25, 1998.

    Issued in Renton, Washington, on February 6, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-3695 Filed 2-17-98; 8:45 am]
BILLING CODE 4910-13-P