AD 96-19-06

[Federal Register Volume 61, Number 180 (Monday, September 16, 1996)]
[Rules and Regulations]
[Pages 48614-48616]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-23099]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-225-AD; Amendment 39-9754; AD 96-19-06]
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 certain Jetstream Model 4101 airplanes. This action 
requires a one-time inspection of the airplane records to determine the 
serial number, the total number of hours time-in-service accumulated, 
and the date of installation of the yaw damper servo in the autopilot 
system; and to determine the date of installation of a particular kit, 
if installed. This action also requires removing and replacing the yaw 
damper servo, or rendering the yaw damper servo inoperative. This 
action also provides for optional terminating action for the 
requirements of this AD. This amendment is prompted by reports of smoke 
in the flight deck due to overheat failure of the Flight Control 
Computer (FCC). The actions specified in this AD are intended to 
prevent such overheat failure, which could result in smoke in the 
flight deck that could inhibit the ability of the flightcrew to safely 
operate and land the airplane.

DATES: Effective October 1, 1996.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 1, 1996.
    Comments for inclusion in the Rules Docket must be received on or 
before November 15, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-225-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,

[[Page 48615]]

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 certain Jetstream Model 
4101 airplanes. The CAA advises that it received several reports 
indicating that smoke was observed in the flight deck of these 
airplanes due to overheat failure of the Flight Control Computer (FCC). 
Investigation revealed that this failure occurred due to contamination 
and internal corrosion of the yaw damper servo, which is mounted in the 
tailcone of the airplane. This condition caused corrosion deposits to 
build up in the pins and shell of the electrical connector of the yaw 
damper servo and consequent electrical breakdown and high current flow 
through the connecting wires to the FCC, which is mounted under the 
flight deck floor. While this current flow was not high enough to trip 
the 7.5A circuit breaker that protects the FCC, it was sufficient to 
cause burning of the circuit boards within the FCC. Such burning, if 
not corrected, could result in smoke in the flight deck, which could 
inhibit the ability of the flightcrew to safely operate and land the 
airplane.

Explanation of Relevant Service Information

    Jetstream has issued Alert Service Bulletin J41-A22-005, dated July 
1, 1996, which describes procedures for a one-time inspection of the 
airplane records (Part 1 of the Accomplishment Instructions) to 
determine the serial number, the total number of hours time-in-service 
accumulated, and the date of installation of the yaw damper servo in 
the autopilot system; and to determine the date of installation of Kit 
JK42716 (reference Jetstream Service Bulletin J41-53-016 or J41-22-
007), if installed. In addition, the alert service bulletin describes 
procedures for accomplishment of one of the following actions after 
accomplishment of the inspection:
     Remove and replace the yaw damper servo (Part 2 of the 
Accomplishment Instructions of the alert service bulletin). Among other 
things, this involves removal of the yaw damper servo; installation of 
a new protective box (Kit JK42716), if not installed previously; an 
inspection of the connector for damage, and replacement of damaged 
parts; installation of a serviceable yaw damper servo; and an 
operational test of the autopilot system.
     Render the yaw damper servo inoperative (Part 3 of the 
Accomplishment Instructions of the alert service bulletin). Among other 
things, this involves disconnecting, capping, and stowing a cable that 
supplies current to the clutch of the yaw damper servo; installation of 
a temporary placard near the autopilot controller; and an operational 
test of the autopilot system.
    Jetstream also has issued Service Bulletin J41-22-006, dated July 
1, 1996, which describes procedures for installation of circuit 
breakers on the avionic relay panel (Kit JK42867) that will open when 
the current through certain servos is more than a set value. This 
installation entails installing a bracket and two circuit breakers on 
the avionic relay panel, re-routing two cables, installing two new 
cables, and performing an operational test of the autopilot system. 
Accomplishment of the installation will prevent overheat failure of the 
FCC. In addition, accomplishment of the installation eliminates the 
need for the one-time inspection, removing and replacing the yaw damper 
servo and installing a new protective box (if not installed 
previously), or rendering the yaw damper servo inoperative.
    The CAA classified these service bulletins as mandatory, and issued 
British airworthiness directive 002-07-96, dated July 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 overheat 
failure of the FCC, which could result in smoke in the flight deck that 
could inhibit the ability of the flightcrew to safely operate and land 
the airplane. This AD requires a one-time inspection of the airplane 
records to determine the serial number, the total number of hours time-
in-service accumulated, and the date of installation of the yaw damper 
servo in the autopilot system; and to determine the date of 
installation of Kit JK42716, if installed. This AD also requires 
removing and replacing the yaw damper servo and installing a new 
protective box (if not installed previously), or rendering the yaw 
damper servo inoperative. This AD also provides for an optional 
terminating action for the requirements of this AD. The actions are 
required to be accomplished in accordance with the service bulletins 
described previously.

Interim Action

    This is considered to be interim action. The FAA may consider 
further rulemaking action to require the accomplishment of the optional 
terminating action currently specified in this AD. However, the 
proposed compliance time for accomplishment of that action is 
sufficiently long so that prior notice and time for public comment will 
be practicable.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this 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.

[[Page 48616]]

    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-225-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 airplane, 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:

96-19-06 Jetstream Aircraft Limited: Amendment 39-9754. Docket 96-
NM-225-AD.

    Applicability: Model 4101 airplanes having serial numbers 41004 
through 41092 inclusive, on which Jetstream Service Bulletin J41-22-
006, dated July 1, 1996 (Kit JK42867), has not been accomplished; 
certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 overheat failure of the Flight Control Computer 
(FCC), which could result in smoke in the flight deck that could 
inhibit the ability of the flightcrew to safely operate and land the 
airplane, accomplish the following:
    (a) Within 14 days after the effective date of this AD, perform 
a one-time inspection of the airplane records to determine the 
serial number, the total number of hours time-in-service 
accumulated, and the date of installation of the yaw damper servo in 
the autopilot system; and to determine the date of installation of 
Kit JK42716 (reference Jetstream Service Bulletin J41-53-016 or J41-
22-007), if installed. Accomplish the inspection in accordance with 
Part 1 of the Accomplishment Instructions of Jetstream Alert Service 
Bulletin J41-A22-005, dated July 1, 1996. Thereafter, either remove 
and replace the yaw damper servo and install Kit JK42716 (if not 
installed previously), or render the yaw damper servo inoperative, 
in accordance with Part 2 or 3 of the alert service bulletin, 
respectively, at the time specified in paragraph (a)(1), (a)(2), or 
(a)(3) of this AD, as applicable.
    (1) If Kit JK42716 has not been installed: Prior to the 
accumulation of 1,000 hours total time-in-service on the yaw damper 
servo, or within 30 days after the effective date of this AD, 
whichever occurs later.
    (2) If Kit JK42716 has been installed and the yaw damper servo 
was installed prior to the installation of Kit JK42716: Prior to the 
accumulation of 1,000 hours total time-in-service on the yaw damper 
servo, or within 30 days after the effective date of this AD, 
whichever occurs later.
    (3) If Kit JK42716 has been installed and the yaw damper servo 
was installed after the installation of Kit JK42716: Prior to the 
accumulation of 3,000 total hours time-in-service on the yaw damper 
servo, or within 30 days after the effective date of this AD, 
whichever occurs later.
    (b) Installation of circuit breakers on the avionic relay panel 
(Kit JK42867) in accordance with Jetstream Service Bulletin J41-22-
006, dated July 1, 1996, constitutes terminating action for the 
requirements of this AD.
    (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-A22-005, dated July 1, 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 October 1, 1996.

    Issued in Renton, Washington, on September 4, 1996.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-23099 Filed 9-13-96; 8:45 am]
BILLING CODE 4910-13-U