AD 96-13-09

[Federal Register Volume 61, Number 126 (Friday, June 28, 1996)]
[Rules and Regulations]
[Pages 33647-33650]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-15954]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-129-AD; Amendment 39-9677; AD 96-13-09]
RIN 2120-AA64


Airworthiness Directives; Jetstream Model 4101 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to all Jetstream Model 4101

[[Page 33648]]

airplanes. This action requires a review of maintenance records to 
determine the time-in-service (TIS) of the bearings in the starter/
generators of both engines. This action also establishes a new TIS 
limit for the bearings, and requires replacement of the starter/
generator unit with a serviceable unit, if necessary. This amendment is 
prompted by reports of controlled in-flight engine shutdowns resulting 
from failure of the bearings in the starter/generator unit. The actions 
specified in this AD are intended to prevent such failure of the 
bearings of the starter/generator, which could cause severe vibrations 
and resultant in-flight shutdown of one or both engines.

DATES: Effective July 15, 1996.
    -The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of July 15, 1996.
    Comments for inclusion in the Rules Docket must be received on or 
before August 27, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-129-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    -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 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.

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) 227-1149.

SUPPLEMENTARY INFORMATION: The Civil Aviation Authority (CAA), which is 
the airworthiness authority for the United Kingdom, recently notified 
the FAA that an unsafe condition may exist on all Jetstream Model 4101 
airplanes. The CAA advises that it has received reports of controlled 
in-flight engine shutdowns. Investigation has revealed that the 
bearings of the direct current (DC) starter/generator failed, which 
resulted in severe vibration. The bearing failures that resulted in 
engine shutdown occurred at 409, 433, and 470 hours time-in-service 
(TIS). These conditions, if not corrected, could result in an in-flight 
engine shutdown.

Explanation of Relevant Service Information

    -Jetstream has issued Alert Service Bulletin J41-A24-036, dated 
February 26, 1996, which describes procedures for reviewing the 
airplane maintenance records to determine the number of hours TIS that 
the bearings of the DC starter/generator have accumulated. The alert 
service bulletin also describes procedures to remove and replace the 
starter/generator units with serviceable units when the bearings have 
reached a certain (reduced) TIS limit. Such replacement of one of the 
starter/generator units (per airplane) when the bearings have reached a 
certain reduced TIS limit, reduces the possibility of the bearings 
failing in both of the starter/generator units on any one airplane 
during the same flight. The CAA classified this service bulletin as 
mandatory and issued United Kingdom airworthiness directive 002-02-96, 
dated March 1, 1996, in order to assure the continued airworthiness of 
these airplanes in the United Kingdom.

FAA's Conclusions

    -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. Pursuant 
to this bilateral airworthiness agreement, the CAA has kept the FAA 
informed of the situation described above. The FAA has examined the 
findings of the CAA, reviewed all available information, and determined 
that AD action is necessary for products of this type design that are 
certificated for operation in the United States.

Explanation of Requirements of Rule

    -Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design registered 
in the United States, this AD is being issued to prevent in-flight 
engine shutdown of both engines on the same flight due to failure of 
the bearings of the starter/generators of the engines and resultant 
severe vibration. This AD requires a review of maintenance records to 
determine the TIS of the bearings in the starter/generators of both 
engines. This action also establishes a new TIS limit for the bearings 
in one of the two starter/generator units on each airplane, and 
requires replacement of the unit with a serviceable unit. The actions 
are required to be accomplished in accordance with the service bulletin 
described previously.

Differences Between Service Bulletin and AD

    Operators should note that the requirements of this AD differ from 
certain TIS recommendations in the referenced alert service bulletin. 
Specifically, this AD establishes a new limit of 300 hours TIS for the 
bearings of one of the starter/generators of each airplane, rather than 
specifying replacement of the unit when 300 hours ``remain'' on the 
unit before scheduled bearing replacement, as indicated in the alert 
service bulletin. The FAA considers that replacement of a unit with 300 
hours ``remaining'' on the unit could permit a unit to operate 
significantly longer than 300 hours TIS if the TIS limit for the unit 
had previously been extended. The FAA finds that specifying a 300-hour 
TIS limit for the bearings of one of the starter/generator units per 
airplane will ensure that, at no one time, will an airplane be 
operating with both starter/generator units having more than 300 hours 
TIS on the bearings. A review of starter/generator unit failure reports 
and consideration of probability of failure requirements in the type 
certification basis for Jetstream Model 4101 airplanes support the 
establishment of a 300-hour TIS limit for the bearings of one of the 
starter/generator units on each airplane. This limit will ensure an 
acceptable level of safety, as related to continued availability of 
power from both engines on Jetstream Model 4101 airplanes. 
Additionally, the manufacturer has notified the FAA that the 
availability of ample parts may be a problem should the AD require both 
starter/generator units to be replaced if their bearings exceed the TIS 
limit. The FAA has determined that limiting the bearings to 300 hours 
TIS on at least one of the starter/generator units on the airplane 
provides an adequate level of safety; therefore, this AD establishes a 
300-hour TIS limit for the bearings of only one of the two starter/
generator units of the airplane.

Interim Action

    This is considered to be interim action. The manufacturer has 
advised that it currently is developing a modification that will 
positively address the unsafe condition addressed by this AD. Once the 
modification is developed, approved, and available, the FAA may 
consider further rulemaking.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this

[[Page 33649]]

regulation, it is found that notice and opportunity for prior public 
comment hereon are impracticable, and that good cause exists for making 
this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire. 
Communications shall identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 96-NM-129-AD.'' The postcard will be date stamped and 
returned to the commenter.

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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, 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 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:

96-13-09  Jetstream Aircraft Limited: Amendment 39-9677. Docket 96-
NM-129-AD.

    Applicability: All Model 4101 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 (c) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent severe vibration of one or both engines, which could 
cause in-flight engine shutdown, accomplish the following:
    (a) Within 7 days after the effective date of this AD, review 
the airplane maintenance records to determine the hours time-in-
service (TIS) accumulated on the bearings in the starter/generator 
units of both engines, in accordance with Jetstream Alert Service 
Bulletin J41-A24-036, dated February 26, 1996.
    (1) If the bearings on both of the starter/generator units have 
accumulated 300 or more hours TIS: Prior to further flight, replace 
at least one of the starter/generator units with a unit having 
bearings with less than 300 hours TIS, in accordance with the alert 
service bulletin.
    (2) If the bearings on one or both starter/generator units have 
bearings with less than 300 hours TIS: Prior to the accumulation of 
300 hours TIS on the bearings on both starter/generator units, 
remove at least one of the units and replace it with a unit having 
bearings with less than 300 hours TIS, in accordance with the alert 
service bulletin.
    (b) As a continuing requirement thereafter: Prior to the 
accumulation of 300 hours TIS on the bearings on both of the 
starter/generator units on the airplane, remove at least one of the 
units and replace it with a unit having bearings with less than 300 
hours TIS, in accordance with Jetstream Alert Service Bulletin J41-
A24-036, dated February 26, 1996.
    (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 
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.
    (e) The actions shall be done in accordance with Jetstream Alert 
Service Bulletin J41-A24-036, dated February 26, 1996. 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 July 15, 1996.


[[Page 33650]]


    Issued in Renton, Washington, on June 17, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-15954 Filed 6-27-96; 8:45 am]
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