[Federal Register Volume 62, Number 179 (Tuesday, September 16, 1997)]
[Proposed Rules]
[Pages 48538-48542]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 97-24489]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-CE-54-AD]
RIN 2120-AA64


Airworthiness Directives; Pilatus Britten-Norman Limited BN-2A, 
BN-2B, and BN-2T Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to adopt a new airworthiness directive 
(AD) that would apply to certain Pilatus Britten-Norman Limited BN-2A, 
BN-2B, and BN-2T series airplanes. This proposal would require revising 
the FAA-approved Airplane Flight Manual (AFM) to specify procedures 
that would 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. The proposed AD is prompted by the results of 
a review of the requirements for certification of these airplanes in 
icing conditions, new information on the icing environment, and icing 
data provided currently to the flight crew. The actions specified by 
the proposed AD are intended to minimize the potential hazards 
associated with operating these airplanes in severe icing conditions by 
providing more clearly

[[Page 48539]]

defined procedures and limitations associated with such conditions.

DATES: Comments must be received on or before October 14, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 97-CE-54-AD, Room 1558, 601 E. 
12th Street, Kansas City, Missouri 64106. Comments may be inspected at 
this location between 8 a.m. and 4 p.m., Monday through Friday, 
holidays excepted.
    This information also may be examined at the Rules Docket at the 
address above.

FOR FURTHER INFORMATION CONTACT: Mr. John P. Dow, Sr., Aerospace 
Engineer, Small Airplane Directorate, Aircraft Certification Service, 
1201 Walnut, suite 900, Kansas City, Missouri 64106, telephone (816) 
426-6932, facsimile (816) 426-2169.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 proposal 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. 97-CE-54-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Central Region, Office of the Assistant Chief Counsel, 
Attention: Rules Docket No. 97-CE-54-AD, Room 1558, 601 E. 12th Street, 
Kansas City, Missouri 64106.

Discussion

    In October 1994, a transport category airplane was involved in an 
accident in which severe icing conditions (believed to be composed of 
freezing drizzle or supercooled large droplets (SLD)) were reported in 
the area. Loss of control of the airplane may have occurred because ice 
accretion on the upper surface of the wing aft of the area protected by 
the ice protection system caused airflow separation, which resulted in 
the ailerons being forced to a right-wing-down control position. There 
also is concern that the autopilot, which was engaged, may have masked 
the unusual control forces generated by the ice accumulation. These 
conditions, if not corrected, could result in a roll upset from which 
the flight crew may be unable to recover.
    The atmospheric conditions (freezing drizzle or SLD conditions) 
that may have contributed to the accident are outside the icing 
envelope specified in Appendix C of part 25 of the Federal Aviation 
Regulations (14 CFR part 25) for certification of the airplane. Such 
icing conditions are not defined in Appendix C, and the FAA has not 
required that airplanes be shown to be capable of operating safely in 
those icing conditions.
    The FAA finds that flight crews are not currently provided with 
adequate information necessary to determine when the airplane is 
operating in icing conditions for which the airplane is not 
certificated or what action to take when such conditions are 
encountered. Therefore, the FAA has determined that flight crews must 
be provided with such information and must be made aware of certain 
visual cues that may indicated the airplane is operating in atmospheric 
conditions that are outside the icing envelope.
    Since such information is not available to flight crews, and no 
airplane is certificated for operation in severe icing conditions, such 
as freezing drizzle or SLD conditions, the FAA finds that the 
potentially unsafe condition (described previously as control 
difficulties following operation of the airplane in icing conditions 
outside the icing envelope) is not limited to airplanes having the same 
type design as that of the accident airplane.
    The FAA recognizes that the flight crew of any airplane that is 
certificated for flight in icing conditions may not have adequate 
information concerning 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 
unpowered roll control systems and pneumatic de-icing boots. 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 issued the following airworthiness directives (AD's) 
that addressed airplanes that met these criteria. These AD's identified 
visual cues for recognizing severe icing conditions, procedures for 
exiting these conditions, and prohibitions on the use of various flight 
control devices. These AD's consisted of the following airplane models.

----------------------------------------------------------------------------------------------------------------
                  Docket No.                      Manufacturer/airplane model       Federal Register citation   
----------------------------------------------------------------------------------------------------------------
96-CE-01-AD..................................  de Havilland DHC-6 Series.......  61 FR 2175                     
96-CE-02-AD..................................  EMBRAER EMB-110P1/EMB-110P2.....  61 FR 2183                     
96-CE-03-AD..................................  Beech 99/200/1900 Series........  61 FR 2180                     
96-CE-04-AD..................................  Dornier 228 Series..............  61 FR 2172                     
96-CE-05-AD..................................  Cessna 208/208B.................  61 FR 2178                     
96-CE-06-AD..................................  Fairchild Aircraft SA226/SA227    61 FR 2189                     
                                                Series.                                                         
96-CE-07-AD..................................  Jetstream 3101/3201.............  61 FR 2186                     
96-NM-13-AD..................................  Jetstream BAe ATP...............  61 FR 2144                     
96-NM-14-AD..................................  Jetstream 4101..................  61 FR 2142                     
96-NM-15-AD..................................  British Aerospace HS 748 Series.  61 FR 2139                     

[[Page 48540]]

                                                                                                                
96-NM-16-AD..................................  Saab SF340A/SAAB 340B/SAAB 2000   61 FR 2169                     
                                                Series.                                                         
96-NM-17-AD..................................  CASA C-212/CN-235 Series........  61 FR 2166                     
96-NM-18-AD..................................  Dornier 328-100 Series..........  61 FR 2157                     
96-NM-19-AD..................................  EMBRAER EMB-120 Series..........  61 FR 2163                     
96-NM-20-AD..................................  de Havilland DHC-7/DHC-8 Series.  61 FR 2154                     
96-NM-21-AD..................................  Fokker F27 Mark 100/200/300/400/  61 FR 2160                     
                                                500/600/700/050 Series.                                         
96-NM-22-AD..................................  Short Brothers SD3-30/SD3-60/SD3- 61 FR 2151                     
                                                SHERPA Series.                                                  
95-NM-146-AD.................................  Aerospatiale ATR-42/ATR-72        61 FR 2147                     
                                                Series.                                                         
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    Since 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. Like the AD's written in 
1996, the proposed rules described below would also provide visual cues 
for recognizing severe icing conditions, procedures for exiting these 
conditions, and prohibitions on the use of various flight control 
devices. These proposed rules would apply to part 25 and certain part 
23 airplanes that are equipped with unpowered aileron controls and 
pneumatic de-icing boots. The part 23 NPRM's address airplanes 
certificated in normal and utility categories (not used in agricultural 
operations) that are used in part 135 on-demand and air-taxi operation, 
and other airplanes regularly exposed to icing conditions. The proposed 
rules affect the following airplanes.

------------------------------------------------------------------------
               Airplane models                         Docket No.       
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Aerospace Technologies of Australia, Models    97-CE-49-AD              
 N22B and N24A.                                                         
Harbin Aircraft Mfg. Corporation, Model Y12    97-CE-50-AD              
 IV.                                                                    
Partenavia Costruzioni Aeronauticas, S.p.A.,   97-CE-51-AD              
 Models P68, AP68TP 300, AP68TP 600.                                    
Industrie Aeronautiche e Meccaniche, Rinaldo   97-CE-52-AD              
 Piaggio S.p.A., Model P-180.                                           
Pilatus Aircraft Ltd., Models PC-12 and PC-12/ 97-CE-53-AD              
 45.                                                                    
Pilatus Britten-Norman Ltd., Models BN-2A, BN- 97-CE-54-AD              
 2B, and BN-2T.                                                         
SOCATA--Groupe Aerospatiale, Model TBM-700...  97-CE-55-AD              
Aerostar Aircraft Corporation, Models PA-60-   97-CE-56-AD              
 600, -601, -601P, -602P, and -700P.                                    
Twin Commander Aircraft Corporation, Models    97-CE-57-AD              
 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..                                                 
Raytheon Aircraft Company (formerly known as   97-CE-58-AD              
 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.                                                       
Raytheon Aircraft Company (formerly known as   97-CE-59-AD              
 Beech Aircraft Corporation), Model 2000.                               
The New Piper Aircraft, Inc., Models PA-46 -   97-CE-60-AD              
 310P and PA-46-350P.                                                   
The New Piper Aircraft, Inc. Models PA-23, PA- 97-CE-61-AD              
 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.                                    
Cessna Aircraft Company, Models P210N, T210N,  97-CE-62-AD              
 P210R, and 337 series.                                                 
Cessna Aircraft Company, Models T303, 310R,    97-CE-63-AD              
 T310R, 335, 340A, 402B, 402C, 404, F406,                               
 414, 414A, 421B, 421C, 425, and 441.                                   
SIAI-Marchetti S.r.I. (Augusta), Models SF600  97-CE-64-AD              
 and SF600A.                                                            
Cessna Aircraft Company, Models 500, 501,      97-NM-170-AD             
 550, 551, and 560 series.                                              
Sabreliner Corporation, Models 40, 60, 70,     97-NM-171-AD             
 and 80 series.                                                         
Gulfstream Aerospace, Model G-159 series.....  97-NM-172-AD             
McDonnell Douglas, Models DC-3 and DC-4        97-NM-173-AD             
 series.                                                                
Mitsubishi Heavy Industries, Model YS-11 and   97-NM-174-AD             
 YS-11A series.                                                         
Frakes Aviation, Model G-73 (Mallard) and G-   97-NM-175-AD             
 73T series.                                                            
Fairchild, Models F27 and FH227 series.......  97-NM-176-AD             
Lockheed Models..............................  97-NM-177-AD             
------------------------------------------------------------------------

The FAA's Determination

    Following examination of all relevant information, the FAA has 
determined that certain limitations and procedures should be included 
in the FAA-approved Airplane Flight Manual (AFM) for the affected 
airplanes as follows:
     All Pilatus Britten-Norman Models BN-2A, BN-2B, and BN-2T 
airplanes must be prohibited from flight in severe icing conditions (as 
determined by certain visual cues), and
     Flight crews must be provided with information that would 
minimize the potential hazards associated with operating the airplane 
in severe icing conditions.
    The FAA has determined that such limitations and procedures 
currently are not defined adequately in the AFM for these airplanes.
    These airplane models are manufactured in England and are type 
certificated for operations in the United States under the provisions 
of Section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement.

Explanation of the Provisions of the Proposed AD

    Since an unsafe condition has been identified which an 
unrecoverable roll upset may occur, as a result of exposure to severe 
icing conditions that are outside the icing limits for which the 
airplanes were certificated, the proposed AD would require revising 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 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

[[Page 48541]]

     Require that all icing wing inspection lights be operative 
prior to flight into known or forecast icing conditions at night.
    This proposed AD would also 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.

Cost Impact

    The FAA estimates that 12 airplanes in the U.S. registry would be 
affected by the proposed AD, that it would take approximately 1 
workhour per airplane to accomplish the proposed action, and that the 
average labor rate is approximately $60 an hour. Since an owner/
operator who holds at least a private pilot's certificate as authorized 
by Secs. 43.7 and 43.11 of the Federal Aviation Regulations (14 CFR 
47.7 and 43.11) can accomplish the proposed action, the only cost 
impact upon the public is the time it would take the affected airplane 
owners/operators to incorporate the proposed AFM revisions.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed requirements of 
this AD action, and that no operator would accomplish those actions in 
the future if this AD were not adopted.
    In addition, the FAA recognizes that the proposed action 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 proposed herein would 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 
proposal would 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) if promulgated, 
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 copy of the draft regulatory evaluation 
prepared for this action has been placed in the Rules Docket. A copy of 
it may be obtained by contacting 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.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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 USC 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:

Pilatus Britten-Norman Limited: Docket No. 97-CE-54-AD.

    Applicability: BN-2A, BN-2B, and BN-2T series 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 (d) 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 already accomplished.
    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 
exists, 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 lower surface of the wing aft of the 
protected area.
--Accumulation of ice on the engine nacelles and propeller spinners 
farther aft than normally observed.

     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 icing detection 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 in the AFM.

``THE FOLLOWING WEATHER CONDITIONS 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.

[[Page 48542]]

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 lower 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) 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) 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) 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, Small Airplane Directorate, FAA, 
1201 Walnut, suite 900, Kansas City, Missouri 64106. 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.

    (e) All persons affected by this directive may examine 
information related to this AD at the FAA, Central Region, Office of 
the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas 
City, Missouri 64106.

    Issued in Kansas City, Missouri, on September 9, 1997.
James E. Jackson,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-24489 Filed 9-15-97; 8:45 am]
BILLING CODE 4910-13-U