[Federal Register Volume 70, Number 232 (Monday, December 5, 2005)]
[Proposed Rules]
[Pages 72406-72409]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-23600]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-23173; Directorate Identifier 2005-NM-190-AD]
RIN 2120-AA64


Airworthiness Directives; Short Brothers Model SD3 Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for all Short Brothers Model SD3 airplanes. This proposed AD would 
require installing additional fuel tank bonding jumpers, performing an 
in-place resistance check of the float switches, inspecting certain 
internal components of the fuel tanks, and performing related 
corrective actions if necessary. This proposed AD would also require 
revisions to the airworthiness limitations section of the Instructions 
for Continued Airworthiness, and to the airplane flight manual 
procedures for operation during icing conditions and fuel system 
failures. This proposed AD results from fuel system reviews conducted 
by the manufacturer. We are proposing this AD to prevent ignition 
sources inside the fuel tanks, which could lead to fire or explosion.

DATES: We must receive comments on this proposed AD by January 4, 2006.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, 
Washington, DC 20590.
     Fax: (202) 493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    Contact Short Brothers, Airworthiness & Engineering Quality, P.O. 
Box 241, Airport Road, Belfast BT3 9DZ, Northern Ireland, for service 
information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT: Dan Rodina, Aerospace Engineer, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2125; fax (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed in the ADDRESSES section. Include the docket number ``FAA-2005-
23173; Directorate Identifier 2005-NM-190-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments received by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that Web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You may review the DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may visit http://dms.dot.gov.

[[Page 72407]]

Examining the Docket

    You may examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif Building at the DOT 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after the Docket Management System 
receives them.

Discussion

    The FAA has examined the underlying safety issues involved in 
recent fuel tank explosions on several large transport airplanes, 
including the adequacy of existing regulations, the service history of 
airplanes subject to those regulations, and existing maintenance 
practices for fuel tank systems. As a result of those findings, we 
issued a regulation titled ``Transport Airplane Fuel Tank System Design 
Review, Flammability Reduction and Maintenance and Inspection 
Requirements'' (67 FR 23086, May 7, 2001). In addition to new 
airworthiness standards for transport airplanes and new maintenance 
requirements, this rule included Special Federal Aviation Regulation 
No. 88 (``SFAR 88,'' Amendment 21-78, and subsequent Amendments 21-82 
and 21-83).
    Among other actions, SFAR 88 requires certain type design (i.e., 
type certificate (TC) and supplemental type certificate (STC)) holders 
to substantiate that their fuel tank systems can prevent ignition 
sources in the fuel tanks. This requirement applies to type design 
holders for large turbine-powered transport airplanes and for 
subsequent modifications to those airplanes. It requires them to 
perform design reviews and to develop design changes and maintenance 
procedures if their designs do not meet the new fuel tank safety 
standards. As explained in the preamble to the rule, we intended to 
adopt airworthiness directives to mandate any changes found necessary 
to address unsafe conditions identified as a result of these reviews.
    In evaluating these design reviews, we have established four 
criteria intended to define the unsafe conditions associated with fuel 
tank systems that require corrective actions. The percentage of 
operating time during which fuel tanks are exposed to flammable 
conditions is one of these criteria. The other three criteria address 
the failure types under evaluation: single failures, single failures in 
combination with another latent condition(s), and in-service failure 
experience. For all four criteria, the evaluations included 
consideration of previous actions taken that may mitigate the need for 
further action.
    The Joint Aviation Authorities (JAA) has issued a regulation that 
is similar to SFAR 88. (The JAA is an associated body of the European 
Civil Aviation Conference (ECAC) representing the civil aviation 
regulatory authorities of a number of European States who have agreed 
to co-operate in developing and implementing common safety regulatory 
standards and procedures.) Under this regulation, the JAA stated that 
all members of the ECAC that hold type certificates for transport 
category airplanes are required to conduct a design review against 
explosion risks.
    We have determined that the actions identified in this AD are 
necessary to reduce the potential of ignition sources inside fuel 
tanks, which, in combination with flammable fuel vapors, could result 
in fuel tank explosions and consequent loss of the airplane.
    The Civil Aviation Authority (CAA), which is the airworthiness 
authority for the United Kingdom, notified us that an unsafe condition 
may exist on all Short Brothers Model SD3 airplanes. The CAA advises 
that ignition sources may develop inside fuel tanks due to insufficient 
grounding. This condition, if not corrected, could result in ignition 
sources occurring inside the fuel tanks, which could lead to fire or 
explosion.

Relevant Service Information

    Short Brothers has issued Service Bulletins SD3 SHERPA-28-2, SD360 
SHERPA-28-3, SD330-28-37, and SD360-28-23; all dated June 2004. The 
service bulletins describe procedures for installing additional bonding 
jumpers between the vent pipes of both fuel tanks and the airplane 
structure; for performing an in-place resistance check of the fuel tank 
float switches; for inspecting the condition of certain sensor cables 
and cable supports inside the fuel tanks; for inspecting the integrity 
of the existing bonding of certain vent pipes inside the forward fuel 
tank; and for performing applicable corrective actions. Corrective 
actions include replacing defective float switches with new, 
reconditioned, or serviceable float switches, and repairing damaged 
sensor cables, cable supports, and existing vent pipe bonding.
    Short Brothers has issued Advance Amendment Bulletin 1/2004, dated 
July 13, 2004, applicable to Shorts airplane flight manuals having Doc. 
Nos. SB.4.3, SB.4.6, SB.4.8, SB.5.2, SB.6.2, SBH.3.2, SBH.3.3, SBH.3.6, 
SBH.3.7, SBH.3.8, and SBH.3.9. The advance amendment bulletin describes 
revisions needed to meet the requirements of FAA SFAR 88 and/or CAA 
Airworthiness Notice AN55; the revisions affect sections of the flight 
manuals applicable to operation during icing conditions and fuel system 
failures.
    Short Brothers has issued temporary revisions (TR) to the 
airworthiness limitations section of the aircraft maintenance manuals 
(AMM) of the affected airplanes, as shown in the following table. The 
TRs address airworthiness limitations to certain components of the fuel 
tank system installations.

                                             AMM Temporary Revisions
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                                    Temporary
        Airplane model               revision                Dated                          To AMM
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SD3-30........................  TR330-AMM-14.....  June 21, 2004............  SD3-30 AMM.
SD3-60........................  TR360-AMM-33.....  July 27, 2004............  SD3-60 AMM.
SD3-60 SHERPA.................  TRSD360S-AMM-14..  July 29, 2004............  SD3-60 SHERPA AMM.
SD3-SHERPA....................  TRSD3S-AMM-15....  July 28, 2004............  SD3-SHERPA AMM.
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    Accomplishing the actions specified in the service information is 
intended to adequately address the unsafe condition. The CAA mandated 
the service information and issued British airworthiness directive G-
2004-0021, dated August 25, 2004, to ensure the continued airworthiness 
of these airplanes in the United Kingdom.

FAA's Determination and Requirements of the Proposed AD

    This airplane model is manufactured in the United Kingdom and are 
type certificated for operation in the United States under the 
provisions of section

[[Page 72408]]

21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the 
applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, the FCAA has kept the FAA informed 
of the situation described above. We have examined the CAA's findings, 
evaluated all pertinent information, and determined that we need to 
issue an AD for airplanes of this type design that are certificated for 
operation in the United States.
    Therefore, we are proposing this AD, which would require 
accomplishing the actions specified in the service information 
described previously, except as discussed under ``Difference Between 
the Proposed AD and Service Information.''

Difference Between Proposed AD and Service Information

    The service bulletins specify to contact the manufacturer for 
instructions on how to repair certain conditions, but this proposed AD 
would require repairing those conditions using a method that we or the 
CAA (or its delegated agent) approve. In light of the type of repair 
that would be required to address the unsafe condition, and consistent 
with existing bilateral airworthiness agreements, we have determined 
that, for this proposed AD, a repair we or the CAA approve would be 
acceptable for compliance with this proposed AD.

Clarification of Inspection Terminology

    In this proposed AD, the ``visual inspection'' specified in the 
Shorts service bulletins is referred to as a ``general visual 
inspection.'' We have included the definition for a general visual 
inspection in a note in the proposed AD.

Costs of Compliance

    This proposed AD would affect about 54 airplanes of U.S. registry. 
The average labor rate is estimated to be $65 per work hour.
    The proposed revisions to the AFM and AMM would take about 1 work 
hour per airplane. Based on these figures, the estimated cost of the 
proposed revisions for U.S. operators is $3,510, or $65 per airplane.
    The proposed resistance check, inspections, and jumper 
installations, would take about 40 work hours per airplane. Required 
parts would cost about $10 per airplane. Based on these figures, the 
estimated cost of these proposed actions for U.S. operators is 
$140,940, or $2,610 per airplane.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
subtitle VII, part A, subpart III, section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect 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.
    For the reasons discussed above, I certify that the 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. 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket. See the 
ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

Short Brothers PLC: FAA-2005-23173; Directorate Identifier 2005-NM-
190-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by January 
4, 2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all Shorts Model SD3-60 SHERPA, SD3-
SHERPA, SD3-30, and SD3-60 airplanes, certificated in any category.

    Note 1: This AD requires revisions to certain operator 
maintenance documents to include new inspections. Compliance with 
these inspections is required by 14 CFR 91.403(c). For airplanes 
that have been previously modified, altered, or repaired in the 
areas addressed by these inspections, the operator may not be able 
to accomplish the inspections described in the revisions. In this 
situation, to comply with 14 CFR 91.403(c), the operator must 
request approval for an alternative method of compliance according 
to paragraph (i) of this AD. The request should include a 
description of changes to the required inspections that will ensure 
the continued damage tolerance of the affected structure. The FAA 
has provided guidance for this determination in Advisory Circular 
(AC) 25-1529.

Unsafe Condition

    (d) This AD results from fuel system reviews conducted by the 
manufacturer. We are issuing this AD to prevent ignition sources 
inside the fuel tanks, which could lead to fire or explosion.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Revision of Airplane Flight Manual (AFM)

    (f) Within 30 days after the effective date of this AD, revise 
the Limitations and Normal Procedures sections of the AFMs as 
specified in Table 1 of this AD to include the information in Shorts 
Advance Amendment Bulletin 1/2004, ``Introduction of Changes to Meet 
the Requirements of FAA SFAR 88 and/or UK CAA Airworthiness Notice 
AN55,'' dated July 13, 2004, as specified in the advance amendment 
bulletin. This advance amendment bulletin addresses operation during 
icing conditions and fuel system failures. Operate the airplane 
according to the limitations and procedures in the advance amendment 
bulletin.

    Note 2: The requirements of paragraph (f) of this AD may be done 
by inserting a copy of the advance amendment bulletin into the AFM. 
When this advance amendment

[[Page 72409]]

bulletin has been included in general revisions of the AFM, the 
general revisions may be inserted into the AFM and the advance 
amendment bulletin may be removed, provided the relevant information 
in the general revision is identical to that in the advance 
amendment bulletin.


                         Table 1.--AFM Revisions
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              Airplane model                AFM documents to be  revised
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SD3-30....................................  SBH.3.2, SBH.3.3, SBH.3.6,
                                             SBH.3.7, SBH.3.8, and
                                             SBH.3.9.
SD3-60....................................  SB.4.3, SB.4.6, and SB.4.8.
SD3-60 SHERPA.............................  SB.5.2.
SD3-SHERPA................................  SB.6.2.
------------------------------------------------------------------------

Revision of Airworthiness Limitation (AWL) Section

    (g) Within 180 days after the effective date of this AD: Revise 
the AWL section of the Instructions for Continued Airworthiness by 
incorporating airplane maintenance manual sections 5-20-01 and 5-20-
02 as introduced by the Shorts temporary revisions (TR) specified in 
Table 1 of this AD into the AWL section of the AMMs for the airplane 
models specified in Table 1. Thereafter, except as provided by 
paragraph (i) of this AD, no alternative structural inspection 
intervals may be approved for the longitudinal skin joints in the 
fuselage pressure shell.

    Note 3: The requirements of paragraph (g) of this AD may be done 
by inserting a copy of the applicable TR into the applicable AMM. 
When the TR has been included in general revisions of the AMM, the 
general revisions may be inserted in the AMM and the TR may be 
removed, provided the relevant information in the general revision 
is identical to that in the TR.


                                        Table 2.--AMM Temporary Revisions
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                                    Temporary
        Airplane model               revision                Dated                          To AMM
----------------------------------------------------------------------------------------------------------------
SD3-30........................  TR330-AMM-14.....  June 21, 2004............  SD3-30 AMM.
SD3-60........................  TR360-AMM-33.....  July 27, 2004............  SD3-60 AMM.
SD3-60 SHERPA.................  TRSD360S-AMM-14..  July 29, 2004............  SD3-60 SHERPA AMM.
SD3-SHERPA....................  TRSD3S-AMM-15....  July 28, 2004............  SD3-SHERPA AMM.
----------------------------------------------------------------------------------------------------------------

Resistance Check, Inspection, and Jumper Installation

    (h) Within 180 days after the effective date of this AD: Perform 
the insulation resistance check, general visual inspections, and 
bonding jumper wire installations; in accordance with Shorts Service 
Bulletin SD330-28-37, SD360-28-23, SD360 SHERPA-28-3, or SD3 SHERPA-
28-2; all dated June 2004; as applicable. If any defects or damage 
are discovered during any inspection or check required by this AD, 
before further flight, repair the defects or damage using a method 
approved by either the Manager, International Branch, ANM-116, 
Transport Airplane Directorate, FAA; or the Civil Aviation Authority 
(CAA) (or its delegated agent).

    Note 4: For the purposes of this AD, a general visual inspection 
is: ``A visual examination of an interior or exterior area, 
installation, or assembly to detect obvious damage, failure, or 
irregularity. This level of inspection is made from within touching 
distance unless otherwise specified. A mirror may be necessary to 
ensure visual access to all surfaces in the inspection area. This 
level of inspection is made under normally available lighting 
conditions such as daylight, hangar lighting, flashlight, or 
droplight and may require removal or opening of access panels or 
doors. Stands, ladders, or platforms may be required to gain 
proximity to the area being checked.''

Alternative Methods of Compliance (AMOCs)

    (i)(1) The Manager, International Branch, ANM-116, Transport 
Airplane Directorate, FAA, has the authority to approve AMOCs for 
this AD, if requested in accordance with the procedures found in 14 
CFR 39.19.
    (2) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

Related Information

    (j) British airworthiness directive G-2004-0021, dated August 
25, 2004, also addresses the subject of this AD.

    Issued in Renton, Washington, on November 25, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-23600 Filed 12-2-05; 8:45 am]
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