[Federal Register Volume 64, Number 46 (Wednesday, March 10, 1999)]
[Rules and Regulations]
[Pages 11761-11764]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-5724]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-CE-65-AD; Amendment 39-11066; AD 99-06-02]
RIN 2120-AA64


Airworthiness Directives; Fairchild Aircraft, Inc. SA226 and 
SA227 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
applies to certain Fairchild Aircraft, Inc. (Fairchild) SA226 and SA227 
series airplanes. This AD requires repetitively inspecting the wing 
spar center web cutout on both wings for cracks between Wing Station 
(WS) 8 and WS 17.5, and immediately repairing any area found cracked. 
This repair will eliminate the need for the repetitive inspections on 
that particular wing spar. This AD is the result of reports of cracks 
in the wing spar center web cutout caused by fatigue due to airplane 
maneuvering and wind gusts. The actions specified by this AD are 
intended to detect and correct fatigue cracking of the wing spar center 
web cutout area, which could result in structural failure of the wing 
spar to the point of failure with consequent loss of control of the 
airplane.

DATES: Effective April 16, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of April 16, 1999.

ADDRESSES: Service information that applies to this AD may be obtained 
from Field Support Engineering, Fairchild Aircraft, Inc., P.O. Box 
790490, San Antonio, Texas 78279-0490; telephone: (210) 824-9421; 
facsimile: (210) 820-8609. This information may also be examined at the 
Federal Aviation Administration (FAA), Central Region, Office of the 
Regional Counsel, Attention: Rules Docket No. 98-CE-65-AD, Room 1558, 
601 E. 12th Street, Kansas City, Missouri 64106; or at the Office of 
the Federal Register, 800 North Capitol Street, NW, suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Mr. Hung Viet Nguyen, FAA, Airplane 
Certification Office, 2601 Meacham Boulevard, Fort Worth, Texas 76193-
0150; telephone: (817) 222-5155; facsimile: (817) 222-5960.

SUPPLEMENTARY INFORMATION:

Events Leading to the Issuance of This AD

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to include an AD that would apply to certain Fairchild 
SA226 and SA227 series airplanes was published in the Federal Register 
as a notice of proposed rulemaking (NPRM) on July 31, 1998 (63 FR 
40846). The NPRM proposed to require repetitively inspecting the wing 
spar center web cutout on both wings for cracks between WS 8 and WS 
17.5, and immediately repairing any area found cracked. This repair 
would eliminate the need for the repetitive inspections on that 
particular wing spar. Accomplishment of the proposed action as 
specified in the NPRM would be required in accordance with the 
following documents:

--Fairchild Airframe Airworthiness Limitations Manual ST-UN-M001, Rev. 
No. C-6, dated April 7, 1998;
--Fairchild Airframe Inspection Manual ST-UN-M002, Rev. No. A-6, dated 
December 8, 1997;
--Fairchild Airframe Airworthiness Limitations Manual ST-UN-M003, Rev. 
No. 5, dated April 7, 1998;
--SA226/227 Series Structural Repair Manual, part number (P/N) 27-
10054-079, pages 57 through 90; Initial Issue: March 1, 1983; Revision 
28, dated June 24, 1998; and
--SA227 Series Structural Repair Manual, P/N 27-10054-127, pages 47 
through 60; Initial Issue: December 1, 1991; Revision 7, dated June 24, 
1998.

    The NPRM was the result of reports of cracks in the wing spar 
center web cutout caused by fatigue due to airplane maneuvering and 
wind gusts.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the following comments.

Comment Issue No. 1: Allow Flight When Cracks in the Wing Spar 
Center Web Do Not Exceed a Certain Length

    Five commenters request that the FAA structure the proposed AD in a 
way that would allow continued flight if cracks were found in the wing 
spar center web cutout provided the cracks did not exceed a certain 
limit. One of these commenters states that, although requiring 
replacement of the wing spar center web if any crack if found is a good 
idea, many airplanes would be grounded while waiting for parts and that 
flight with a small crack is not necessarily unsafe.
    The FAA does not concur that flight should be allowed with cracks 
in the wing spar center web cutout regardless of the size of the 
cracks. Extensive analysis of the consequences of flying with known 
cracks in primary structure prompted the FAA to establish a policy that 
disallows airplane operation when these cracks exist. In certain 
circumstances, the FAA would allow flight with minor cracks provided an 
acceptable inspection and replacement schedule was submitted. Among the 
criteria for allowing flight with minor cracks are as follows:

     Substantiation that the cracks are not in primary 
structure;
     Substantiation that the cracks are in fail-safe 
structure. Various combinations of analysis and test, including that 
provided at the time of original certification, may be considered as 
ample substantiation. This must include the ability to sustain 
ultimate load with the maximum permissible crack. Other valid 
substantiations that may be considered include various combinations 
of fracture mechanics analysis, flight test, ground test. Temporary 
repairs such as ``stop drilling'' should be specified; or
     Substantiation to verify that the single load path 
structure with the known cracks has the ability to carry ultimate 
loads. Various combinations of fracture mechanics analysis, flight 
test, ground test, or proof test may be considered as ample 
substantiation. Only when unusual circumstances exist, such as the 
difficulty of an operator in obtaining replacement parts, will this 
be allowed.

    Under no circumstances can any of these exceptions be considered as 
more than a temporary condition.
    The FAA has not received information and documentation that meet 
any of the above criteria. Therefore, no changes are necessary to the 
final rule as a result of these comments.

[[Page 11762]]

Comment Issue No. 2: Compliance Times in the Proposed AD Are 
Different Than Those Specified in the Applicable Service 
Information

    Three commenters question why the FAA did not differentiate the 
compliance times of the SA226 series airplanes and the SA227 series 
airplanes. In particular, the Airframe Airworthiness Limitations 
Manuals specify an initial inspection time of 6,500 hours time-in-
service (TIS) for the SA226 series airplanes and 10,600 hours TIS for 
the SA227 series airplanes. In addition, the Airframe Airworthiness 
Limitations Manuals specify repetitive inspection intervals of 3,000 
hours TIS while the proposed AD specifies intervals of 2,000 hours TIS.
    Individual commenters make the following points:

--The justification for the difference in compliance times is due to 
the design of the number 13 stringer cut-out in the wing spar center 
web being different in the SA226 series airplanes and the SA227 series 
airplanes.
--Experience shows that cracking in the affected area seems to be a 
problem on airplanes with over 10,000 hours TIS, but no cracks have 
been found by the individual commenter on airplanes with around 6,500 
hours TIS. The commenter recommends that the FAA establish the initial 
inspection at 8,500 hours TIS.
--If the 2,000 hours TIS repetitive inspection interval is going to be 
used instead of 3,000 hours TIS, then the FAA needs to justify why 
2,000 hours TIS is needed rather than what is already specified in the 
Airframe Airworthiness Limitations Manual.

    The FAA does not concur that the compliance time of either the 
initial or repetitive inspection should be changed. Cracks do not 
always occur in all airplanes, nor do the cracks that develop on 
airplanes occur at the same time. Airplanes are operated in different 
environments and flight loads depending on the area of the country or 
world they are operated in or the type of operation they are routinely 
utilized for (e.g., commuter, cargo, general aviation, etc.), 
respectively. These factors contribute to the development of cracks and 
the crack growth rate of existing cracks. At the time that the Airframe 
Airworthiness Limitations Manuals were published, there were no cracks 
found in the wing spar center web cutout on in-service airplanes. The 
inspection intervals specified in these manuals were based on one full-
scale fatigue test of an SA226 series airplane. The SA227 series 
airplanes have not been full-scale fatigue tested in the affected area. 
Based on analysis of all information on this subject received to date, 
the FAA has determined that the initial inspection compliance time of 
6,500 hours TIS and the repetitive inspection interval of 2,000 hours 
TIS on all affected airplanes is justified.
    No changes are necessary to the final rule as a result of these 
comments.

Comment Issue No. 3: AD Concurrence

    One commenter supports the AD as written. This commenter feels that 
the proposed AD would meet the safety intent of detecting and 
correcting fatigue cracking of the wing spar center web cutout area of 
Fairchild SA226 and SA227 series airplanes.

Comment Issue No. 4: Remove the SA227 Series Airplanes From the 
Applicability of the Proposed AD

    Two commenters state that the actions proposed in the AD are not 
necessary for the SA227 series airplanes because the Fairchild Airframe 
Airworthiness Limitations Manual ST-UN-M001 and ST-UN-M003 make these 
requirements mandatory for continued airworthiness. The commenters 
state that since these inspections are already required, the SA227 
series airplanes should be removed from the Applicability of the 
proposed AD.
    The FAA concurs that the proposed inspections are currently 
required, particularly by Secs. 135.411 and 135.425 of the Federal 
Aviation Regulations (14 CFR 135.411 and 14 CFR 135.425) for airplanes 
``type certificated for a passenger seating configuration, excluding 
any pilot seat, of ten seats or more, * * *'' The SA227 series 
airplanes fall in this category. However, as discussed in the Comment 
Issue No. 2 section of this document, the inspection compliance times 
of the proposed AD differ from that specified in the Fairchild Airframe 
Airworthiness Limitations Manual ST-UN-M001 and ST-UN-M003. In 
addition, SA227 series airplanes that have been or are at a later date 
altered from the original 10 or more seat configuration (either through 
a supplemental type certificate or other FAA-approved method) may no 
longer be required by 14 CFR 135.411 and 14 CFR 135.425 to have the 
actions of the above-referenced Airframe Airworthiness Limitations 
Manuals accomplished. In this case, the only mechanism of assuring that 
the actions are accomplished is through the issuance of an AD.
    The FAA has determined (1) that the compliance times specified in 
the proposed AD should take precedence over those specified in the 
Airframe Limitation Manuals (see Comment Issue No. 2 in this document); 
and (2) that the inspections should be required on any SA227 series 
airplane that has had the 10 or more seat configuration altered. For 
these reasons, the only change necessary to the final rule as a result 
of these comments is a statement that gives initial inspection credit 
to the owners/operators of those airplanes that are currently in 
compliance with the applicable Airframe Airworthiness Limitations 
Manual.

Comment Issue No. 5: Account for Future Revisions to the Service 
Manuals

    Two commenters recommend that the words ``or later revision'' be 
added to each reference to the Airworthiness Airworthiness Limitations 
Manuals and the Structural Repair Manual (SRM). This would allow any 
future revisions to automatically be incorporated into the AD.
    The FAA does not concur. The FAA cannot approve data that does not 
exist. Approval of this nature could adversely affect aviation safety 
if documentation was included in the subsequent service information 
that did not carry normal FAA review or was FAA-approved, but included 
information that did not accomplish the intent of the AD.
    No changes have been made to the final rule as a result of these 
comments.

The FAA's Determination

    After careful review of all available information related to the 
subject presented above, the FAA has determined that air safety and the 
public interest require the adoption of the rule as proposed except for 
the addition of language that gives ``already accomplished'' credit for 
those owners/operators of those affected airplanes that are in 
compliance with the applicable Airframe Airworthiness Limitations 
Manual and minor editorial corrections. The FAA has determined that 
this addition and these minor editorial corrections will not change the 
meaning of the AD and will not add any additional burden upon the 
public than was already proposed.

Cost Impact

    The FAA estimates that 490 airplanes in the U.S. registry will be 
affected by this AD, that it will take approximately 5 workhours per 
airplane to accomplish the initial inspection, and that the average 
labor rate is approximately $60 an hour. Based on these figures, the 
total cost impact of the initial inspection specified in this AD on 
U.S. operators is estimated to be $147,000, or $300 per airplane.

[[Page 11763]]

    These figures only take into account the costs of the initial 
inspection and do not take into account the costs of repetitive 
inspections and the costs associated with any repair that will be 
necessary if cracks are found. The FAA has no way of determining the 
number of repetitive inspections an owner/operator will incur over the 
life of the airplane, or the number of airplanes that will need 
repairs.
    If an affected airplane has cracks in both wing spar center webs, 
the repair will take approximately 400 workhours to accomplish at an 
average labor rate of $60 per hour. Parts to accomplish this repair 
cost approximately $400 per airplane. Based on these figures, the cost 
to repair cracked wing spar center webs on both sides of the airplane 
will be approximately $24,400 per airplane.

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.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under 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. A copy of the final 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, 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 a new airworthiness directive 
(AD) to read as follows:

99-06-02  Fairchild Aircraft, Inc.: Amendment 39-11066; Docket No. 
98-CE-65-AD.

    Applicability: The following model airplanes and serial numbers, 
certificated in any category:

------------------------------------------------------------------------
            Model                              Serial No.
------------------------------------------------------------------------
SA226-AT.....................  AT001 through AT074.
SA226-TC.....................  TC201 through TC419.
SA226-T......................  T201 through T291.
SA226-T(B)...................  T(B)276 and T(B)292 through T(B)417.
SA227-TT.....................  TT421 through TT541.
SA227-TT(300)................  TT(300)447, TT(300)465, TT(300)471,
                                TT(300)483, TT(300)512, TT(300)518,
                                TT(300)521, TT(300)527, TT(300)529, and
                                TT(300)536.
SA227-AC.....................  AC406, AC415, AC416, and AC420 through
                                AC785.
SA227-AT.....................  AT423 through AT631 and AT695.
SA227-BC.....................  BC762, BC764, BC766, and BC770 through
                                BC789.
SA227-CC/DC..................  CC/DC784 and CC/DC790 through CC/DC878.
------------------------------------------------------------------------

    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 (e) 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 in the body of this AD, unless 
already accomplished.
    To detect and correct fatigue cracking of the wing spar center 
web cutout area, which could result in structural failure of the 
wing spar to the point of failure with consequent loss of control of 
the airplane, accomplish the following:
    (a) Upon accumulating 6,500 hours time-in-service (TIS) on each 
wing spar; within the next 2,000 hours TIS after the last inspection 
accomplished per the applicable Airworthiness Limitations Manual 
(referenced in the paragraphs below); or within the next 500 hours 
TIS after the effective date of this AD, whichever occurs later, 
unless already accomplished; and thereafter at intervals not to 
exceed 2,000 hours TIS, inspect each wing spar center web cutout for 
cracks between Wing Station (WS) 8 and WS 17.5. Accomplish this 
inspection in accordance with one of the following, as applicable:
    (1) For Models SA227-TT, SA227-AT, SAA227-AC, and SA227-BC 
airplanes: In accordance with Fairchild Airframe Airworthiness 
Limitations Manual ST-UN-M001, Rev. No. C-6, dated April 7, 1998;
    (2) For Models SA226-T, SA226-T(B), SA226-AT, and SA226-TC 
airplanes: In accordance with Fairchild Airframe Inspection Manual 
ST-UN-M002, Rev. No. A-6, dated December 8, 1997; or
    (3) For Models SA227-CC and SA227-DC airplanes: In accordance 
with Fairchild Airframe Airworthiness Limitations Manual ST-UN-M003, 
Rev. No. 5, dated April 7, 1998.
    (b) If any crack(s) is/are found during any inspection required 
by paragraph (a) of this AD, prior to further flight, repair the 
crack(s) in accordance with one of the following, as applicable. 
This repair eliminates the repetitive inspections (2,000 hours TIS 
intervals) required in paragraph (a) of this AD for that particular 
wing spar.
    (1) For Models SA226-T, SA226-T(B), SA226-AT, SA226-TC, SA227-
TT, SA227-AT, SA227-AC, and SA227-BC airplanes: In accordance with 
Fairchild SA226/227 Series Structural Repair Manual, part number (P/
N) 27-10054-079, pages 57 through 90; Initial Issue: March 1, 1983; 
Revision 28, dated June 24, 1998; or
    (2) For Models SA227-CC and SA227-DC airplanes: In accordance 
with Fairchild SA227 Series Structural Repair Manual, P/N 27-10054-
127, pages 47 through 60; Initial Issue: December 1, 1991; Revision 
7, dated June 24, 1998.
    (c) The repetitive inspections required by paragraph (a) of this 
AD may be terminated if the wing spar center web repair specified in 
paragraph (b) of this AD has been

[[Page 11764]]

accomplished on both the left and right wing spar. If one wing spar 
center web has been repaired, then repetitive inspections are still 
required on the other one if the repair has not been incorporated.
    (d) Special flight permits may be issued in accordance with 
Secs. 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) An alternative method of compliance or adjustment of the 
initial or repetitive compliance times that provides an equivalent 
level of safety may be approved by the Manager, FAA, Airplane 
Certification Office (ACO), 2601 Meacham Boulevard, Fort Worth, 
Texas 76193-0150. The request shall be forwarded through an 
appropriate FAA Maintenance Inspector, who may add comments and then 
send it to the Manager, Forth Worth ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Fort Worth ACO.

    (f) The inspections required by this AD shall be done in 
accordance with Fairchild Airframe Airworthiness Limitations Manual 
ST-UN-M001, Rev. No. C-6, dated April 7, 1998; Fairchild Airframe 
Inspection Manual ST-UN-M002, Rev. No. A-6, dated December 8, 1997; 
or Fairchild Airframe Airworthiness Limitations Manual ST-UN-M003, 
Rev. No. 5, dated April 7, 1998, as applicable. The possible repairs 
required by this AD shall be done in accordance with Fairchild 
SA226/227 Series Structural Repair Manual, part number (P/N) 27-
10054-079, pages 57 through 90; Initial Issue: March 1, 1983; 
Revision 28, dated June 24, 1998; or Fairchild SA227 Series 
Structural Repair Manual, P/N 27-10054-127, pages 47 through 60; 
Initial Issue: December 1, 1991; Revision 7, dated June 24, 1998, as 
applicable. 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 Field Support 
Engineering, Fairchild Aircraft, Inc., P.O. Box 790490, San Antonio, 
Texas 78279-0490. Copies may be inspected at the FAA, Central 
Region, Office of the Regional Counsel, Room 1558, 601 E. 12th 
Street, Kansas City, Missouri, or at the Office of the Federal 
Register, 800 North Capitol Street, NW, suite 700, Washington, DC.
    (g) This amendment becomes effective on April 16, 1999.

    Issued in Kansas City, Missouri, on February 26, 1999.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 99-5724 Filed 3-9-99; 8:45 am]
BILLING CODE 4910-13-U