[Federal Register Volume 61, Number 209 (Monday, October 28, 1996)]
[Proposed Rules]
[Pages 55585-55587]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-27521]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-85-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 adoption of a new airworthiness 
directive (AD) that is applicable to certain Jetstream Model 4101 
airplanes. This proposal would require an inspection to determine the 
thickness of the intercostal that attaches the third crew member seat 
to the floor structure

[[Page 55586]]

in the flight compartment, and replacement, if necessary. This proposal 
is prompted by a report from the manufacturer indicating that 
intercostals have been installed that are not of sufficient thickness 
(and consequent strength) to support the third crew member seat during 
emergency landing dynamic conditions. The actions specified by the 
proposed AD are intended to prevent the failure of this intercostal 
during an emergency landing, which could consequently result in injury 
to the flight crew.

DATES: Comments must be received by December 9, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-85-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 
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-85-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-85-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    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 4101 airplanes. The CAA 
advises that it has received a report from the manufacturer indicating 
that some intercostals that attach the third crew member seat (``third 
crew seat'') to the floor structure in the flight compartment may not 
have been manufactured using material of the correct thickness. 
Consequently, these parts may lack the necessary strength to withstand 
the stresses exerted during emergency landing dynamic conditions.
    Material stresses existing in the intercostal during an emergency 
landing are a function of the weight of the third crew seat, the weight 
of the person in the seat, and the weight of the carry-on items in the 
forward right stowage compartment. Although an intercostal manufactured 
from material of the incorrect thickness can support the seat and the 
person sitting in it when the total weight of carry-on items in the 
forward right stowage compartment is limited to 100 pounds or less, 
this intercostal could fail when the carry-on items stored in this 
compartment exceed this limit. Installation of an intercostal that is 
not of sufficient thickness (and consequent strength) could result the 
failure of the intercostal during an emergency landing, which could 
cause the third crew seat to become detached from the floor structure 
in the flight compartment. This condition, consequently, could result 
in injury to the flight crew.

Explanation of Relevant Service Information

    Jetstream has issued Alert Service Bulletin J41-A53-030, dated 
January 19, 1996, which describes procedures for inspecting the 
intercostal that attaches the third seat to the floor structure in the 
flight compartment to determine whether this part is manufactured from 
material having the correct thickness. Parts manufactured from material 
having an incorrect thickness are to be replaced with new parts having 
the correct material thickness.
    The service bulletin also describes an optional placarding 
procedure to prohibit use of the third crew seat when the total weight 
contained in the forward right stowage area of the airplane exceeds 100 
pounds. (This area is where the flight crew generally stows its carry-
on items.)
    The CAA classified this service bulletin as mandatory and issued 
British airworthiness directive 006-01-96, dated February 7, 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 require inspection of the 
intercostal which attaches the third crew seat to the floor structure 
in the flight compartment to determine the thickness of this part; and 
replacement with a new intercostal of the correct thickness, if 
necessary. The proposed AD also would provide for use of a temporary, 
optional placarding procedure that entails prohibiting the use of the 
third crew seat under certain conditions until the intercostal is 
replaced. The actions would be required to be accomplished in 
accordance with the service bulletin described previously.

[[Page 55587]]

Cost Impact

    The FAA estimates that 15 Jetstream Model 4101 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 
inspection, 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 $900, 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.

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:

Jetstream Aircraft Limited: Docket 96-NM-85-AD.

    Applicability: Model 4101 airplanes, as listed in Jetstream 
Alert Service Bulletin J41-A53-030, dated January 19, 1996; 
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 (d) 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 failure during emergency landing dynamic conditions 
of the intercostal that attaches the third crew member seat (``third 
crew seat'') to the floor structure in the flight compartment, which 
could consequently result in injury to the flight crew, accomplish 
the following:
    (a) Within 30 days after the effective date of this AD, inspect 
the intercostal in the floor structure that supports the third crew 
seat in the flight compartment to determine the thickness of this 
part, in accordance with Part 1 of Jetstream Alert Service Bulletin 
J41-A53-030, dated January 19, 1996.
    (b) If the thickness of the intercostal is 0.064 inch, no 
further action is required by this AD.
    (c) If the thickness of the intercostal is 0.048 inch, 
accomplish the actions specified in either paragraph (c)(1) or 
(c)(2) of this AD.
    (1) Prior to further flight, replace the intercostal with a new 
part manufactured from material having the correct thickness, in 
accordance with Jetstream Alert Service Bulletin J41-A53-030, dated 
January 19, 1996. After replacement, no further action is required 
by this AD. Or
    (2) Prior to further flight, install a placard, in accordance 
with Jetstream Alert Service Bulletin J41-A53-030, dated January 19, 
1996, to prohibit use of the third crew seat when the total weight 
of carry-on items stored in the forward right stowage area is more 
than 100 pounds. Within 6 months after installation of the placard, 
replace the intercostal with a new part manufactured from material 
having the correct thickness, in accordance with the service 
bulletin. After installation of the new intercostal, the placard may 
be removed.
    (d) 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.

    (e) 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 21, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-27521 Filed 10-25-96; 8:45 am]
BILLING CODE 4910-13-U