[Federal Register Volume 61, Number 135 (Friday, July 12, 1996)]
[Proposed Rules]
[Pages 36667-36669]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-17740]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-122-AD]
RIN 2120-AA64


Airworthiness Directives; Short Brothers Model SD3-60 SHERPA 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all Short Brothers Model SD3-60 
SHERPA series airplanes. This proposal would require revising the 
Airplane Flight Manual (AFM) to provide the flight crew with 
recognition cues for, and procedures for exiting from, severe icing 
conditions, and to limit or prohibit the use of various flight control 
devices. This proposal 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 the proposed 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.

DATES: Comments must be received by August 29, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-122-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    This information may be examined at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Greg Dunn, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2799; fax (206) 227-1149.

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 shall 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 summarizing 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 Number 96-NM-122-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, Transport Airplane Directorate, ANM-103, Attention: Rules 
Docket No. 96-NM-122-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On April 24, 1996, the FAA issued 18 AD's (see below for a listing 
of all 18 AD's) to require revising the FAA-approved Airplane Flight 
Manual (AFM) to provide the flight crew with recognition cues for, and 
procedures for exiting from, severe icing conditions, and to limit or 
prohibit the use of various flight control devices. These AD's were 
published in the Federal Register on May 7, 1996:

----------------------------------------------------------------------------------------------------------------
                                                               Amendment                                        
          Manufacturer/airplane model               AD No.        No.            Federal Register citation      
----------------------------------------------------------------------------------------------------------------
de Havilland DHC-6 Series......................     96-09-11      39-9587  61 FR 20616                          
EMBRAER EMB-110P1/EMB-110P2....................     96-09-12      39-9588  61 FR 20636                          
Beech 99/200/1900 Series.......................     96-09-13      39-9589  61 FR 20638                          
Dornier 228 Series.............................     96-09-14      39-9590  61 FR 20639                          
Cessna 208/208B................................     96-09-15      39-9591  61 FR 20641                          
Fairchild Aircraft SA226/SA227 Series..........     96-09-16      39-9592  61 FR 20643                          
Jetstream 3101/3201............................     96-09-17      39-9593  61 FR 20644                          
Jetstream BAe ATP..............................     96-09-18      39-9594  61 FR 20668                          
Jetstream 4101.................................     96-09-19      39-9595  61 FR 20669                          
British Aerospace HS 748 Series................     96-09-20      39-9596  61 FR 20671                          
Saab SF340A/SAAB 340B/SAAB 2000 Series.........     96-09-21      39-9597  61 FR 20672                          
CASA C-212/CN-235 Series.......................     96-09-22      39-9598  61 FR 20674                          
Dornier 328-100 Series.........................     96-09-23      39-9599  61 FR 20676                          
EMBRAER EMB-120 Series.........................     96-09-24      39-9600  61 FR 20677                          
de Havilland DHC-7/DHC-8 Series................     96-09-25      39-9601  61 FR 20679                          
Fokker F27 Mark 100/200/300/400/500/600/700/050     96-09-26      39-9602  61 FR 20681                          
 Series.                                                                                                        
Short Brothers SD3-30/SD3-60/SD3-SHERPA Series.     96-09-27      39-9603  61 FR 20682                          
Aerospatiale ATR-42/ATR-72 Series..............     96-09-28      39-9604  61 FR 20646                          
----------------------------------------------------------------------------------------------------------------

    Those actions were 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.

[[Page 36668]]

The requirements of those AD's 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.
    Since the issuance of those AD's, the FAA has determined that Short 
Brothers Model SD3-60 SHERPA series airplanes were omitted 
inadvertently from the list of airplane models subject to the 
potentially unsafe condition described previously and addressed in 
those AD's.
    This airplane model is manufactured in the United Kingdom and is 
type certificated for operation 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 Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, the 
proposed AD would require revising the AFM to provide the flight crew 
with recognition cues for, and procedures for exiting from, severe 
icing conditions, and to limit or prohibit the use of various flight 
control devices.

Cost Impact

    The FAA estimates that 20 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 1 work 
hour per airplane to accomplish the proposed actions, and that the 
average labor rate is $60 per work hour. Based on these figures, the 
cost impact of the proposed AD on U.S. operators is estimated to be 
$1,200, or $60 per airplane.
    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 this proposed AD may impose 
operational costs. However, those costs are incalculable because the 
frequency of occurrence of the specified conditions and the associated 
additional flight time are indeterminable. Nevertheless, because of the 
severity of the unsafe condition addressed, the FAA has determined that 
continued operational safety necessitates the imposition of these 
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 proposed 
regulation (1) Is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the 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 is contained 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 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Short Brothers, PLC: Docket 96-NM-122-AD.

    Applicability: All Model SD3-60 SHERPA 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 must 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 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.

     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 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 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 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.

[[Page 36669]]

     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 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 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, Standardization Branch, ANM-113, 
FAA, Transport Airplane Directorate. Operators shall submit their 
requests through an appropriate FAA Principal Operations Inspector, 
who may add comments and then send it to the Manager, 
Standardization Branch, ANM-113.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (c) Special flight permits may be issued in accordance with 
Secs. 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.

    Issued in Renton, Washington, on July 8, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-17740 Filed 7-11-96; 8:45 am]
BILLING CODE 4910-13-U