[Federal Register Volume 61, Number 206 (Wednesday, October 23, 1996)]
[Proposed Rules]
[Pages 54967-54969]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-27239]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-243-AD]
RIN 2120-AA64


Airworthiness Directives; Jetstream Model 4101 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Jetstream Model 
4101 airplanes, that currently 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. That AD also requires 
removing and replacing the yaw damper servo, or rendering the yaw 
damper servo inoperative. The actions specified by that AD are intended 
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. This action 
would require installation of circuit breakers on the avionics relay 
panel, which, when accomplished, would constitute terminating action 
for the previous requirements of the AD.

DATES: Comments must be received by December 3, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-243-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.
    The service information referenced in the proposed rule 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.

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:

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

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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-243-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-243-AD, 1601 Lind Avenue SW., Renton, Washington 
98055-4056.

Discussion

    On September 4, 1996, the FAA issued AD 96-19-06, amendment 39-9754 
(61 FR 48614, September 16, 1996), applicable to certain Jetstream 
Model 4101 airplanes, to require 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. That AD also requires 
removing and replacing the yaw damper servo, or rendering the yaw 
damper servo inoperative. That action was prompted by reports of smoke 
in the flight deck 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. The actions specified in this AD are 
intended to prevent such overheat failure.

Actions Since Issuance of Previous Rule

    When AD 96-19-06 was issued, it contained a provision for the 
optional installation of circuit breakers on the avionics relay panel, 
which, if installed, would constitute terminating action for the 
requirements of the AD. In the preamble to AD 96-19-06, the FAA 
indicated that it intended to revise that AD to require the 
installation of circuit breakers on the avionics relay panel. This 
action proposes such a requirement.

Explanation of Relevant Service Information

    Jetstream issued Service Bulletin J41-22-006, dated July 1, 1996, 
which describes procedures for installation of circuit breakers on the 
avionics relay panel (Kit JK42867) that will open when the current 
through certain autopilot servos is more than a set value. This 
installation entails installing a bracket and two circuit breakers on 
the avionics 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 when any failure occurs in the rudder/yaw damper servo system or 
elevator servo system that results in excessive current flow to the 
servos. 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 Civil Aviation Authority (CAA), which is the airworthiness 
authority for the United Kingdom, classified this service bulletin 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 Proposed 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, the proposed AD would supersede AD 96-19-06. It 
would continue to require 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. It also would continue 
to require removing and replacing the yaw damper servo, or rendering 
the yaw damper servo inoperative. These actions would be required to be 
accomplished in accordance with Jetstream Alert Service Bulletin J41-
22-005, dated July 1, 1996.
    This new proposed AD would require installation of circuit breakers 
on the avionics relay panel. Accomplishment of the installation would 
constitute terminating action for the previous requirements of the 
(existing) AD. The installation would be required to be accomplished in 
accordance with Jetstream Service Bulletin J41-A22-006, dated July 1, 
1996, described previously.

FAA's Determination Relative to Terminating Actions

    The FAA has determined that long term continued operational safety 
will be better assured by modifications or design changes to remove the 
source of the problem, rather than by attempting to eliminate all 
possible failures of the autopilot rudder/yaw damper servo system or 
elevator servo system that result in excessive current flow to the 
servos. The proposed modification requirement is in consonance with 
this consideration.

Cost Impact

    There are approximately 55 Jetstream Model 4101 airplanes of U.S. 
registry that would be affected by this proposed AD.
    The actions that are currently required by AD 96-19-06 take 
approximately 2 to 5 work hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. Based

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on these figures, the cost impact on U.S. operators of the actions 
currently required is estimated to be between $6,600 and $16,500, or 
between $120 and $300 per airplane.
    The new action (installation) that is proposed in this AD action 
would take approximately 3 work hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. Required parts would be 
provided by the manufacturer at no cost to operators. Based on these 
figures, the cost impact on U.S. operators of the proposed installation 
requirement of this AD is estimated to be $9,900, or $180 per airplane.
    Based on the figures discussed above, the (combined) cost impact of 
this proposed AD on U.S. operators would be between $16,500 and 
$26,400, or between $300 and $480 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.

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 removing amendment 39-9754 (61 FR 
48614, September 16, 1996), and by adding a new airworthiness directive 
(AD), to read as follows:

Jetstream Aircraft Limited: Docket 96-NM-243-AD. Supersedes AD 96-
19-06, Amendment 39-9754.

    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 
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 October 1, 1996 (the effective date of 
AD 96-19-06), 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 October 1, 1996, 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 October 1, 1996, 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 October 1, 1996, whichever occurs 
later.
    (b) Within 90 days after the effective date of this AD, install 
circuit breakers on the avionics relay panel (Kit JK42867) in 
accordance with Jetstream Service Bulletin J41-22-006, dated July 1, 
1996. Accomplishment of this installation constitutes terminating 
action for the requirements of paragraph (a) 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.

    Issued in Renton, Washington, on October 17, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-27239 Filed 10-22-96; 8:45 am]
BILLING CODE 4910-13-U