[Federal Register Volume 59, Number 93 (Monday, May 16, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-8177]


[[Page Unknown]]

[Federal Register: May 16, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-NM-98-AD; Amendment 39-8872; AD 94-08-01]

 

Airworthiness Directives; British Aerospace Model ATP 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 British Aerospace Model ATP airplanes, that requires 
revising the Airplane Flight Manual (AFM) to prohibit flight in certain 
freezing precipitation conditions. This AD also provides an optional 
terminating action for the AFM revision. This amendment is prompted by 
reports of engine power rollback (loss of engine power) that occurred 
in environmental conditions involving freezing precipitation. The 
actions specified by this AD are intended to prevent loss of multiple 
engine power during flight in freezing precipitation.

DATES: Effective June 15, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of June 15, 1994.

ADDRESSES: The service information referenced in this AD may be 
obtained from Jetstream Aircraft, Inc., P.O. Box
16029, Dulles International Airport, Washington, DC 20041-6029. This 
information may be examined at the Federal Aviation Administration 
(FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, 
SW., Renton, Washington; or at the Office of the Federal Register, 800 
North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: William Schroeder, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2148; fax (206) 227-1320.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations to include an airworthiness directive (AD) that is 
applicable to all British Aerospace Model ATP airplanes was published 
in the Federal Register on September 3, 1993 (58 FR 46916). That action 
proposed to require revising the Airplane Flight Manual (AFM) to 
prohibit flight in certain freezing precipitation conditions.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter supports the proposed rule, but suggests that the 
action should have been issued to require immediate compliance to 
reduce the traveling public's exposure to the potential risk of loss of 
multiple engine power during flight in freezing precipitation and 
possible unplanned landings. The commenter also requests that, since 
the AD was issued as a proposal, the time required for publication of 
the final rule in the Federal Register be kept to a minimum so as not 
to induce an additional administrative delay that would only delay 
compliance.
    The FAA does not concur with the commenter's suggestion that the 
final rule be issued to require immediate compliance. At the time of 
issuance of the proposal, the FAA could not justify that an immediate 
safety of flight problem existed, especially in light of the fact that 
the single operator of the entire U.S. fleet of Model ATP airplanes 
already had added an operating restriction similar to that required by 
this AD to its FAA-approved operation specifications and had agreed to 
operate in accordance with that restriction until further corrective 
action could be identified and incorporated. Moreover, the operating 
limitation was proposed by the FAA since, at that time, the airplane 
manufacturer, the Civil Aviation Authority (CAA), which is the 
airworthiness authority for the United Kingdom, and the FAA were 
uncertain as to the cause of the engine power rollback problem 
described in the preamble to the proposal. However, considerable 
information was available at that time to indicate that the problem was 
due to ice ingestion into the engines during certain meteorological 
conditions. That data, however, had not yet been confirmed through 
testing conducted by the manufacturer and the CAA. Consequently, the 
FAA determined that a requirement to prohibit flight in certain 
freezing precipitation conditions would provide an acceptable level of 
safety until terminating action could be identified and developed.
    In developing this AD action, the FAA considered all of these 
items, and determined that, since the continued operational safety of 
the U.S. fleet could be assured during the interim, it was not 
impracticable to provide notice and the opportunity for public comment 
on the proposed rule.
    Two commenters, the CAA and Jetstream, request that the proposed 
rule be revised to require establishing a life limit on the engine 
igniter plugs, installing a bypass duct outlet eductor, and 
incorporating other changes to the airplane flight manual (AFM), in 
lieu of the proposed AFM revision. The commenters contend that, if such 
interim measures are taken, an acceptable level of safety would be 
assured pending longer term corrective action. The commenters explain 
that service information has been issued that describes procedures for 
those actions, as follows:
    1. Jetstream Service Bulletin ATP-80-06, Revision 1, dated October 
22, 1993, which describes procedures for placing a life limit on the 
engine igniter plugs and replacing those parts at staggered periods in 
order to improve ignition reliability.
    2. Jetstream Service Bulletin ATP-54-12-35274A, Revision 1, dated 
December 15, 1993, which describes procedures for installation of an 
eductor plate over the exhaust port of the engine air intake system. 
Accomplishment of this installation will increase the air flow rate 
down the exhaust port.
    3. Temporary Revision No. T/33, Issue 1, dated November 1, 1993, 
which revises AFM Document No. ATP 004. This temporary revision 
describes revisions to the Limitations and Normal Procedures sections 
of the FAA-approved AFM to introduce procedures for operation in icing 
conditions. The changes include a ground inspection of the engine inlet 
prior to flight, staggered selection of the left- and right-hand engine 
de-ice systems to ensure that the likelihood of simultaneous engine 
rundown on final approach is minimized, and a small increase in the 
final approach speed to ensure safe landing.
    Jetstream also suggests two other alternatives that would provide 
an adequate level of safety, wherein the proposed AFM limitation could 
be removed:
    1. Modification of the engine inlets, in addition to accomplishment 
of the interim measures discussed previously (a life limit on the 
engine igniter plugs, installation of a bypass duct outlet eductor, and 
certain changes to the AFM). Jetstream indicates that these modified 
engine inlets demonstrate a significant improvement in de-icing 
effectiveness in the range of temperatures and airplane speeds in which 
power rollbacks have been experienced.
    Jetstream service bulletins that relate to the engine inlet 
modification are described as follows: Jetstream Service Bulletin ATP-
54-13-35274B, dated October 9, 1993, describes procedures for 
installing engine air inlet ducts that incorporate electrical de-ice 
heaters with increased power and area. The service bulletin also 
describes procedures for performing associated electrical system 
changes. The installation involves installing engine air inlet ducts 
that incorporate an enlarged heater mat with revised electrical power 
densities adjacent to the engine intake flange. Jetstream Service 
Bulletin ATP-54-14, dated October 14, 1993, describes procedures for 
repetitive visual inspections of the heater mats for damage, and 
replacement of the engine air intake, if necessary.
    2. Accomplishment of special operating procedures, not specifically 
defined by the commenter. Jetstream considers that requiring such 
operating procedures is a proven and acceptable means of providing an 
adequate level of safety, as generally demonstrated by the operation of 
aircraft throughout their flight spectra, in accordance with AFM's.
    Jetstream submits one final suggestion in the event the FAA 
proceeds with requiring the proposed operating limitation. In this 
case, the commenter suggests that the actions described in Jetstream 
Service Bulletins ATP-54-13-35274B and ATP-54-14, in addition to the 
interim measures discussed previously (a life limit on the engine 
igniter plugs, installation of a bypass duct outlet eductor, and 
certain changes to the AFM), be accomplished as an alternative method 
of compliance for the proposed operating limitation.
    The FAA concurs partially. The interim measures proposed by the CAA 
and Jetstream were based, to a large extent, on the flight crew 
performing special operating procedures to ensure a safe landing after 
one or both engines had run down due to ice ingestion. However, the FAA 
considers that requiring the flight crew to perform such special 
operating procedures over a long term period may not provide the degree 
of safety assurance necessary for these airplanes. The FAA has 
determined that requiring the proposed operating limitation to prohibit 
flight into certain meteorological conditions known to cause engine 
rundown will provide an acceptable level of safety until additional 
hardware modifications can be identified and installed on these 
airplanes.
    However, the FAA concurs with Jetstream's suggestion that the 
accomplishment of the interim measures and modification of the engine 
inlets may be accomplished as optional terminating action for the 
operating limitation. Since the issuance of the proposed rule, 
Jetstream has issued Temporary Revision No. T/38, Issue 1, dated 
February 16, 1994, which revises certain pages of Temporary Revision 
No. T/33 (discussed previously). Temporary Revision No. T/38 amends the 
Normal Procedures section of the AFM as related to operation of engine 
continuous ignition during flight in icing conditions. The FAA finds 
that this new information must be included in the AFM for Model ATP 
airplanes in order to assure continued reliability and to prevent 
unnecessary wear on engine ignition systems.
    Accordingly, the final rule has been revised to include a new 
paragraph (b), which includes the following optional terminating 
action:
    1. Revising the Limitations section and the Normal and Abnormal 
Procedures sections of the FAA-approved AFM, to include the information 
specified in Temporary Revision No. T/33, Issue 1, dated November 1, 
1993, and Temporary Revision No. T/38, Issue 1, dated February 16, 
1994, to introduce procedures for operation in icing conditions.
    2. Revising the FAA-approved maintenance program to place a life 
limit on the engine igniter plugs and to replace those parts at 
specified intervals in accordance with Jetstream Service Bulletin ATP-
80-06, Revision 1, dated October 22, 1993.
    3. Installing an eductor plate over the exhaust port of the engine 
air intake system in accordance with Jetstream Service Bulletin ATP-54-
12-35274A, Revision 1, dated December 15, 1993.
    4. Installing engine air inlet ducts that incorporate electrical 
de-ice heaters with increased power and area, and performing associated 
electrical system changes, in accordance with Jetstream Service 
Bulletin ATP-54-13-35274B, dated October 9, 1993.
    5. Revising the FAA-approved maintenance program to include 
repetitive visual inspections of the heater mats for damage; and, if 
any damage is found, replacement of the engine air intake; in 
accordance with Jetstream Service Bulletin ATP-54-14, dated October 14, 
1993. -
    This is considered to be interim action until final action is 
identified, at which time the FAA may consider further rulemaking.
    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 changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    The FAA estimates that 9 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 AFM revision, and that the average 
labor rate is $55 per work hour. The cost for required parts is 
expected to be negligible. Based on these figures, the total cost 
impact of the AD on U.S. operators is estimated to be $495, or $55 per 
airplane. This total cost figure assumes that no operator has yet 
accomplished the requirements of this AD.
    Should an operator elect to accomplish the optional terminating 
action that is provided by this AD action, the number of work hours 
required to accomplish it is approximately 159 per airplane, at an 
average labor rate of $55 per work hour. Required modification parts 
would be supplied by Jetstream at no cost to operators. Based on these 
figures, the total cost impact of the AD for accomplishment of the 
optional terminating action is $8,745 per airplane.
    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, Incorporation by 
reference, Safety.
Adoption of the Amendment
    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 14 CFR part 
39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:
94-08-01  British Aerospace (Commercial Aircraft), Limited: 
Amendment 39-8872. Docket 93-NM-98-AD.

    Applicability: All Model ATP airplanes, certificated in any 
category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent loss of multiple engine power during flight in 
freezing precipitation, accomplish the following:
    (a) Within 30 days after the effective date of this AD, revise 
the Limitations Section of the FAA-approved Airplane Flight Manual 
(AFM) to include the following statement. This may be accomplished 
by inserting a copy of this AD in the AFM.
    ``Flight is prohibited into forecast or reported freezing 
precipitation conditions where the outside air temperature is 
between +5  deg.C and -5  deg.C.''
    (b) Accomplishment of the actions specified in paragraphs 
(b)(1), (b)(2), (b)(3), (b)(4), and (b)(5) constitutes terminating 
action for the AFM revision required by paragraph (a) of this AD.
    (1) Revise the Limitations section and the Normal Procedures 
section of the FAA-approved AFM, to include the information 
specified in Temporary Revision No. T/33, Issue 1, dated November 1, 
1993, and Temporary Revision No. T/38, Issue 1, dated February 16, 
1994, which introduce procedures for operation in icing conditions, 
as specified in the temporary revision; and operate the airplane in 
accordance with those limitations and procedures.

    Note 1: This may be accomplished by inserting copies of 
Temporary Revision No. T/33 and No. T/38 in the AFM. When these 
temporary revisions have been incorporated into general revisions of 
the AFM, the general revisions may be inserted in the AFM, provided 
the information contained in the general revisions is identical to 
that specified in Temporary Revision No. T/33 and No. T/38.

    (2) Incorporate a revision into the FAA-approved maintenance 
program that provides for replacement of engine igniter plugs at the 
intervals specified in Jetstream Service Bulletin ATP-80-06, 
Revision 1, dated October 22, 1993. Initial replacement of an engine 
igniter plug with a new plug shall be accomplished prior to the 
accumulation of 200 total hours time-in-service on the engine 
igniter plug, or within 50 hours time-in-service after incorporating 
the maintenance program revision, whichever occurs later. -
    (3) Install an eductor plate over the exhaust port of the engine 
air intake system in accordance with Jetstream Service Bulletin ATP-
54-12-35274A, dated September 28, 1993, or Revision 1, dated 
December 15, 1993. Any eductor plate installed in accordance with 
the original issue of the service bulletin must be inspected for any 
aperture profile mismatch, in accordance with paragraph 2., Part B., 
of the Accomplishment Instructions of Revision 1 of the service 
bulletin. If any mismatch is found that exceeds the limit specified 
in that service bulletin, prior to further flight, the discrepancy 
must be corrected in accordance with paragraph 2., Part C, of 
Revision 1 of the service bulletin.
    (4) Install engine air inlet ducts that incorporate electrical 
de-ice heaters with increased power and area, and perform associated 
electrical system changes, in accordance with Jetstream Service 
Bulletin ATP-54-13-35274B, dated October 9, 1993.
    (5) Revise the FAA-approved maintenance program to include 
repetitive visual inspections of the heater mats for damage at 
intervals not to exceed 50 hours time-in-service, in accordance with 
Jetstream Service Bulletin ATP-54-14, dated October 14, 1993; and, 
if any damage is found, prior to further flight, replace the engine 
air intake, in accordance with the service bulletin.
    (c) 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 Maintenance Inspector, 
who may add comments and then send it to the Manager, 
Standardization Branch, ANM-113.
    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.
    (d) Special flight permits may be issued in accordance with 
Federal Aviation Regulations (FAR) 21.197 and 21.199 to operate the 
airplane to a location where the requirements of this AD can be 
accomplished.
    (e) The actions shall be done in accordance with the following 
documents, as applicable, which contain the specified effective 
pages: 

------------------------------------------------------------------------
 Service bulletin                                                       
  referenced and    Page No.    Revision level shown  Date shown on page
     date-----                        on page-                          
------------------------------------------------------------------------
Temporary Revision        1-5  1....................  November 1, 1993. 
 No. T/33; Issue                                                        
 1, November 1,                                                         
 1993.                                                                  
Temporary Revision   1-2, 7-8  1....................  February 16, 1994.
 No. T/38; Issue          3-4  (These pages are                         
 1, February 16,          5-6   removed).             March 5, 1993.    
 1994.                         Original                                 
ATP 80-06;                1-3  1....................  October 22, 1993. 
 Revision 1,                                                            
 October 22, 1993.                                                      
ATP-54-13-35274B,       1-44-  Original.............  October 9, 1993.  
 October 9, 1993.                                                       
ATP-54-14, October        1-5  Original.............  October 14, 1993. 
 14, 1993.                                                              
ATP-54-12-35274A,   1-3, 5, 7  Original.............  September 28,     
 September 28,           4, 6  (These pages are not    1993.            
 1993.                          used)                                   
ATP-54-12-35274A;   1-5, 7, 9  1....................  December 15, 1993.
 Revision 1,             6, 8  (These pages are not                     
 December 15, 1993.             used)                                   
------------------------------------------------------------------------

    This incorporation by reference was approved by the Director of 
the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR 
part 51. Copies may be obtained from Jetstream Aircraft, Inc., P.O. 
Box 16029, Dulles International Airport, Washington, DC 20041-6029. 
Copies may be inspected at the FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington; or at the Office of the 
Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.
    (f) This amendment becomes effective on June 15, 1994.
    Issued in Renton, Washington, on March 31, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-8177 Filed 5-13-94; 8:45 am]
BILLING CODE 4910-13-U