
[Federal Register: August 23, 2010 (Volume 75, Number 162)]
[Proposed Rules]               
[Page 51696-51698]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr23au10-20]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0042; Directorate Identifier 2009-NM-010-AD]
RIN 2120-AA64

 
Airworthiness Directives; Saab AB, Saab Aerosystems Model SAAB 
340A (SAAB/SF340A) and SAAB 340B Airplanes Modified in Accordance With 
Supplemental Type Certificate (STC) SA00224WI-D, ST00146WI-D, or 
SA984GL-D

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Supplemental notice of proposed rulemaking (NPRM); reopening of 
comment period.

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SUMMARY: We are revising an earlier proposed airworthiness directive 
(AD) for certain Saab AB, Saab Aerosystems Model SAAB 340A (SAAB/
SF340A) and SAAB 340B airplanes. The original NPRM would have required 
inspecting the fuselage surface for corrosion and cracking behind the 
external adapter plate of the antennae installation, and repair if 
necessary. The original NPRM resulted from a report of a crack found 
behind the external adapter plate of the antennae during inspection. 
Similar cracking was found on two additional airplanes, and extensive 
corrosion was found on one airplane. This action revises the original 
NPRM by correcting an STC number, which would expand the applicability 
of the original NPRM. We are proposing this supplemental NPRM to detect 
and correct corrosion and cracking behind the external adapter plate of 
the antennae of certain damage-tolerant structure, which could result 
in reduced structural integrity and consequent rapid depressurization 
of the airplane.

DATES: We must receive comments on this supplemental NPRM by September 
17, 2010.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://
www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

FOR FURTHER INFORMATION CONTACT: William Griffith, Aerospace Engineer, 
Airframe Branch, ACE-118W, FAA, Wichita Aircraft Certification Office, 
1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 
67209; telephone (316) 946-4116; fax (316) 946-4107.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2010-0042; 
Directorate Identifier 2009-NM-010-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    We issued a notice of proposed rulemaking (NPRM) (the ``original 
NPRM'') to amend 14 CFR part 39 to include an airworthiness directive 
(AD) that would apply to certain Saab AB, Saab Aerosystems Model SAAB 
340A (SAAB/SF340A) and SAAB 340B airplanes. That original NPRM was 
published in the Federal Register on January 19, 2010 (75 FR 2829). 
That original NPRM proposed to require inspecting the fuselage surface 
for corrosion and cracking behind the external adapter plate of the 
antennae installation, and repair if necessary.

Actions Since Original NPRM Was Issued

    Since we issued the original NPRM, we have determined that STC 
number SA00244WI-D, identified in the applicability of the NPRM, is an 
incorrect STC number; the correct number is SA00224WI-D. We have 
corrected this error, which expands the airplanes affected by the 
original NPRM.

Comments

    We gave the public the opportunity to participate in developing 
this AD. We considered the comments received.

Request To Change the Description of the Unsafe Condition

    Saab AB/Aerosystems asks that we change the description of the 
unsafe condition specified in the NPRM. Saab states that the NPRM 
indicates that the fuselage skin is classified as ``certain safe-life 
structure.'' Saab notes that this does not meet the definition of the 
airframe/fuselage structure; the fuselage skin is damage tolerant 
structure according to Section 25.571 of the Federal Aviation 
Regulations (14 CFR 25.571). Saab adds that this definition is included 
in the fatigue critical baseline structure (FCBS) list.
    We agree with the commenter for the reasons provided. We have 
changed the description of the unsafe condition in the Summary section 
and paragraph (e) of this AD accordingly.

[[Page 51697]]

Request To Define Method To Repair Discrepancies

    Saab asks that we define the method necessary to repair the 
discrepancies specified in the NPRM. Saab states that the NPRM does not 
give any details on how to repair those discrepancies. Saab adds that 
the method in the NPRM specifies that only approval by the Manager, 
Wichita Aircraft Certification Office (ACO), will be accepted.
    We disagree with the commenter. The discrepancies referred to in 
this AD are corrosion, and cracking of the fuselage surface as a result 
of that corrosion. Each airplane may exhibit different extremes of both 
types of corrosion and cracking, and each repair must be evaluated by 
the ACO based on the extent of the damage. We have not changed the AD 
in this regard.

Request to Re-Evaluate the STC Procedures

    Saab states that it has reservations about the STC procedures for 
installation of the TCAS antennae because of the possibility of 
compromised long-term effects on the airplane. Saab notes that the 
installation procedures include anchor nuts installed directly in the 
skin without anchor nut places, acceptance of improper edge distances, 
compromised surface protection, and no structural reinforcement of the 
antennae.
    We infer that Saab is requesting re-evaluation of the STC 
procedures; we do not agree. The STC was approved by us in 1991, and 
there is not enough data at this time to warrant re-evaluation of the 
STC procedures. Corrosion issues are more than likely the result of the 
initial installer applying inadequate corrosion protection as indicated 
by the initial fleet data. Without additional fleet data to confirm 
otherwise, we cannot concur with any design inadequacies. Therefore, we 
have not changed the AD in this regard.

Request To Include Replacement Procedure for the Adapter Plate

    Saab asks that a replacement procedure for corroded adapter plates 
be included in Chapter 51-70-60 of the Saab Structural Repair Manual 
(SRM). Saab states that typical installation of the antennae and 
associated actions is outlined in the SRM, and the antennae plates are 
subject to corrosion. Saab adds that a replacement procedure for the 
adapter plate should be included in the SRM to allow operators to 
install replacement plates according to design procedures.
    We acknowledge and agree with the commenter's concern that the STC 
holder should have provided appropriate procedures for replacement of 
corroded adapter plates. Once STC procedures are developed, approved, 
and available, we might consider additional rulemaking. However, we 
consider that any further delay in issuing this supplemental NPRM would 
result in an unacceptable level of risk because doing so would allow 
the unsafe condition to continue for an indefinite length of time. 
Therefore, we have not changed the AD in this regard.

FAA's Determination and Proposed Requirements of the Supplemental NPRM

    We are proposing this supplemental NPRM because we evaluated all 
pertinent information and determined an unsafe condition exists and is 
likely to exist or develop on other products of these same type 
designs. Certain changes described above expand the scope of the 
original NPRM. As a result, we have determined that it is necessary to 
reopen the comment period to provide additional opportunity for the 
public to comment on this supplemental NPRM.

Explanation of Change to Costs of Compliance

    Since issuance of the original NPRM, we have increased the labor 
rate used in the Costs of Compliance from $80 per work-hour to $85 per 
work-hour. The Costs of Compliance information, below, reflects this 
increase in the specified hourly labor rate.

Costs of Compliance

    We estimate that this proposed AD would affect 201 airplanes of 
U.S. registry. The proposed inspection would take about 4 work hours 
per airplane, at an average labor rate of $85 per work hour. Based on 
these figures, the estimated cost of the proposed AD for U.S. operators 
is $68,340, or $340 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 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 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. 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.
    You can find our regulatory evaluation and the estimated costs of 
compliance in the AD Docket.

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 FAA amends Sec.  39.13 by adding the following new AD:

Saab AB, Saab Aerosystems: Docket No. FAA-2010-0042; Directorate 
Identifier 2009-NM-010-AD.

Comments Due Date

    (a) We must receive comments by September 17, 2010.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to the Saab AB, Saab Aerosystems airplanes, 
certificated in any category, identified in paragraphs (c)(1) and 
(c)(2) of this AD, that have been modified in

[[Page 51698]]

accordance with Supplemental Type Certificate (STC) SA00224WI-D, 
ST00146WI-D, or SA984GL-D.
    (1) Model SAAB 340A (SAAB/SF340A) airplanes, serial numbers 004 
through 159 inclusive.
    (2) Model SAAB 340B airplanes, serial numbers 160 through 459 
inclusive.

Subject

    (d) Air Transport Association (ATA) of America Code 53: 
Fuselage.

Unsafe Condition

    (e) This AD results from a report of a crack found behind the 
external adapter plate of the antennae during inspection. Similar 
cracking was found on two additional airplanes, and extensive 
corrosion was found on one airplane. The Federal Aviation 
Administration is issuing this AD to detect and correct corrosion 
and cracking behind the external adapter plate of the antennae of 
certain damage-tolerant structure, which could result in reduced 
structural integrity and consequent rapid depressurization of the 
airplane.

Compliance

    (f) You are responsible for having the actions required by this 
AD performed within the compliance times specified.

Inspection/Corrective Actions

    (g) Within 600 flight cycles after the effective date of this 
AD: Remove the external adapter plate of the antennae installation 
and do a general visual inspection of the fuselage surface for 
corrosion and cracking behind the external adapter plate of the 
antennae installation. If any corrosion or cracking is found, repair 
before further flight. If no corrosion or cracking is found, before 
further flight, ensure that proper corrosion protection has been 
applied before reinstalling the adapter plate. Do all the actions 
required by this paragraph in accordance with a method approved by 
the Manager, Wichita Aircraft Certification Office (ACO), FAA.

    Note 1: 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.''

Reporting Requirement

    (h) At the applicable time specified in paragraph (h)(1) or 
(h)(2) of this AD: Submit a report of the positive findings of the 
inspections required by paragraph (g) of this AD. Send the report to 
the Manager, Wichita ACO. The report must contain, at a minimum, the 
inspection results, a description of any discrepancies found, the 
airplane serial number, and the number of flight cycles and flight 
hours on the airplane since installation of the STC. Under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), 
the Office of Management and Budget (OMB) has approved the 
information collection requirements contained in this AD and has 
assigned OMB Control Number 2120-0056.
    (1) If the inspection was done on or after the effective date of 
this AD: Submit the report within 30 days after the inspection.
    (2) If the inspection was done before the effective date of this 
AD: Submit the report within 30 days after the effective date of 
this AD.

Special Flight Permit

    (i) Special flight permits, as described in Section 21.197 and 
Section 21.199 of the Federal Aviation Regulations (14 CFR 21.197 
and 21.199), may be issued to operate the airplane to a location 
where the requirements of this AD can be accomplished, but 
concurrence by the Manager, Wichita ACO, FAA, is required prior to 
issuance of the special flight permit.

Alternative Methods of Compliance (AMOCs)

    (j)(1) The Manager, Wichita ACO, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. Send information to ATTN: William Griffith, 
Aerospace Engineer, Airframe Branch, ACE-118W, FAA, Wichita ACO, 
1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 
67209; telephone (316) 946-4116; fax (316) 946-4107.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your principal maintenance inspector (PMI) or 
principal avionics inspector (PAI), as appropriate, or lacking a 
principal inspector, your local Flight Standards District Office. 
The AMOC approval letter must specifically reference this AD.


    Issued in Renton, Washington on August 16, 2010.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2010-20852 Filed 8-20-10; 8:45 am]
BILLING CODE 4910-13-P

