[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:
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Model Serial No.
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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.
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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