AD 94-07-10 SUPERSEDED

This amendment adopts a new airworthiness directive (AD) that applies to certain Fairchild Aircraft SA226 and SA227 series airplanes. This action requires repetitively inspecting (visually) the wing skin for cracks; dye penetrant inspecting the spar straps if the wing skin is found cracked; and, if any crack is found in the spar straps, repairing the spar straps and modifying the wing skin. This action also provides the option of modifying the wing skin as terminating action for the repetitive inspections. Reports of wing skin cracking because of repeated bending of the wing during service on several of the affected airplanes prompted this action. The actions specified by this AD are intended to prevent failure of the wing skin at the top aft outboard corner of the battery box, which could result in structural damage to the wing.

Final rule.

94-07-10 FAIRCHILD AIRCRAFT: Amendment 39-8868; Docket No. 93-CE-21-AD.

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

Model
Serial Numbers
SA226-T
T201 through T275, and T277 through T291
SA226-T(B)
T(B)276, and T(B)292 through T(B)417
SA226-AT
AT001 through AT074
SA226-TC
TC201 through TC419
SA227-TT
TT421 through TT541
SA227-AT
AT423 through AT631, and AT695
SA227-AC
AC406, AC415, AC416, and AC420 through AC789
SA227-BC
BC420 through BC789
SA227-CC
CC784, and CC790 through CC822
SA227-DC
DC784, and DC790 through DC822

Compliance: Required initially upon the accumulation of 2,500 hours time-in-service (TIS) or within the next 100 hours TIS after the effective date of this AD, whichever occurs later, unless already accomplished, and thereafter as indicated in the body of the AD.

To prevent failure of the wing skin at the top aft outboard corner of the battery box, which could result in structural damage to the wing, accomplish the following:

NOTE 1: The paragraph structure of this AD is as follows:

Level 1:
(a), (b), (c), etc.
Level 2:
(1), (2), (3), etc.
Level 3:
(i), (ii), (iii), etc.

Level 2 and Level 3 structures are designations of the Level 1 paragraph they immediately follow.

(a) Visually inspect the right and left upper skin by the top aft outboard corner of the battery box for cracks in accordance with Figure 1 and the ACCOMPLISHMENT INSTRUCTIONS, A. Inspection, section of whichever of the following is applicable:

(1) Fairchild Service Bulletin (SB) 226-57-018, Issued: January 28, 1993, Revised: June 3, 1993 (pages 4 through 11 and 13 through 15), Revised: July 1, 1993 (page 12) and Revised: October 25, 1993 (pages 1 through 3);

(2) Fairchild SB 227-57-005, Issued: December 21, 1992, Revised: June 3, 1993 (pages 2 through 11 and 13 through 15), and Revised: July 1, 1993 (pages 1 and 12); or

(3) Fairchild Aircraft SB CC7-57-002, Issued: January 28, 1993, Revised: June 3, 1993 (pages 2 through 11 and 13 through 15), and Revised: July 1, 1993 (pages 1 and 12).

(b) If cracks are not found during the visual inspection required by paragraph (a) of this AD, within 500 hours TIS after this initial visual inspection, accomplish one of the following:

(1) Reinspect the right and left upper wing skin by the top aft outboard corner of the battery box for cracks in accordance with Figure 1 and the ACCOMPLISHMENT INSTRUCTIONS, A. Inspection, section of the applicable service information presented in paragraphs (a)(1), (a)(2), and (a)(3) of this AD, and reinspect thereafter at intervals not to exceed 500 hours TIS; or

(2) Modify the upper wing skin in accordance with the ACCOMPLISHMENT INSTRUCTIONS, B. Removal and C. Installation, section of the service information referenced in paragraphs (a)(1), (a)(2), or (a)(3) of this AD, as applicable. Accomplishing this modification terminates the repetitivevisual inspections that are specified in paragraph (b)(1) of this AD, and the modification may be accomplished at any time to eliminate this repetitive inspection requirement.

(c) If cracks are found during the inspection required by paragraph (a) of this AD, prior to further flight, dye penetrant inspect the 27-31130 straps in accordance with the ACCOMPLISHMENT INSTRUCTIONS, B. Removal section, paragraph (7), of the service information referenced in paragraphs (a)(1), (a)(2), or (a)(3) of this AD, as applicable.

(1) If cracks are found in either of the 27-31130 straps during the inspection required by paragraph (c) of this AD, prior to further flight, accomplish the following:

(i) Repair the 27-31130 strap in accordance with a scheme obtained from the manufacturer through the Fort Worth Airplane Certification Office at the address specified in paragraph (d) of this AD; and

(ii) Modify the upper wing skin in accordance with the ACCOMPLISHMENT INSTRUCTIONS, B. Removal and C. Installation, section of the service information referenced in paragraphs (a)(1), (a)(2), or (a)(3) of this AD, as applicable.

(2) If no cracks are found in either of the 27-31130 straps, within 150 hours TIS after the initial dye penetrant inspection required by paragraph (c) of this AD, accomplish one of the following:

(i) Reinspect (dye penetrant) the edges of the spar straps (27-31130) in the wheel wells for cracks in accordance with the ACCOMPLISHMENT INSTRUCTIONS, B. Removal, section of the service information referenced in paragraphs (a)(1), (a)(2), or (a)(3) of this AD, as applicable, and if no cracks are found, continue to reinspect at intervals not to exceed 150 hours TIS; or

(ii) Modify the upper wing skin in accordance with the ACCOMPLISHMENT INSTRUCTIONS, B. Removal and C. Installation, section of the service information referenced in paragraphs (a)(1), (a)(2), or (a)(3) of this AD, as applicable. Accomplishing this modification terminates the repetitive dye penetrant inspections that are specified in paragraph (c)(2)(i) of this AD, and the modification may be accomplished at any time to eliminate this repetitive inspection requirement.

NOTE 2: Certain Limited Approve Repair (LAR) and Approved Repair Procedure (ARP) documents issued by Fairchild Aircraft specify procedures for accomplishing the same modification referenced in paragraphs (b)(2), (c)(1)(ii), and (c)(2)(ii). Check with the Fort Worth Airplane Certification Office at the address presented in paragraph (e) of this AD to find out which LAR's and ARP's are considered "unless already accomplished" as they relate to this AD.

(d) Special flight permits may be issued in accordance with 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, Airplane Certification Office, FAA, 2601 Meacham Boulevard, Fort Worth, Texas 76137-0150. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Fort Worth Airplane Certification Office.

NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Fort Worth Airplane Certification Office.

(f) The inspections and modification required by this AD shall be done in accordance with Fairchild Service Bulletin 226-57-018, Issued: January 28, 1993, Revised: June 3, 1993 (pages 4 through 11 and 13 through 15), Revised: July 1, 1993 (page 12), and Revised: October 25, 1993 (pages 1 through 3); Fairchild Service Bulletin 227-57-005, Issued: December 21, 1992, Revised: June 3, 1993 (pages 2 through 11 and 13 through 15), and Revised: July 1, 1993 (pages 1 and 12); or Fairchild Aircraft Service Bulletin CC7-57-002, Issued: January 28, 1993, Revised: June 3, 1993 (pages 2 through 11 and 13 through 15), and Revised: July 1, 1993 (pages 1 and 12). 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 Fairchild Aircraft, P.O. Box 790490, San Antonio, Texas 78279-0490. Copies may be inspected at the FAA, Central Region, Office of the Assistant Chief 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 May 27, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations to include an AD that would apply to certain Fairchild Aircraft SA226 and SA227 series airplanes was published in the Federal Register on October 4, 1993 (58 FR 51583). The action proposed to require repetitively inspecting (visually) the wing skin for cracks; dye penetrant inspecting the spar straps if the wing skin is found cracked; and, if any crack is found in the spar straps, repairing the spar straps and modifying the wing skin. This action also proposed providing the option of modifying the wing skin as terminating action for the repetitive inspections. The proposal would require accomplishing the actions in accordance with the following service bulletins (SB), as applicable:

Fairchild SB 226-57-018, Issued: January 28, 1993, Revised: June 3, 1993 (pages 2 through 11 and 13 through 15), and Revised: July 1, 1993 (pages 1 and 12);

Fairchild SB 227-57-005, Issued: December 21, 1992, Revised: June 3, 1993 (pages 2 through 11 and 13 through 15), and Revised: July 1, 1993 (pages 1 and 12); or

Fairchild Aircraft SB CC7-57-002, Issued: January 28, 1993, Revised: June 3, 1993 (pages 2 through 11 and 13 through 15), and Revised: July 1, 1993 (pages 1 and 12).

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the three comments received.

One commenter, Ameriflight, states that the liquid penetrant inspection required on the part number (P/N) 2731130 straps when there is a crack in the wing skin is unjustified. Ameriflight conducted a survey of a number of SA226 and SA227 series airplane owners (a total of 101 airplanes). From this survey, Ameriflight found that 57 airplanes had at least one wing with a skin crack evident. None of these 57 have any cracks in the strap, with many of the airplanes having in excess of 20,000 hours time-in-service (TIS), and no incident of cracking in these straps has ever occurred according to information provided by the Fort Worth Airplane Certification Office. Ameriflight believes that the FAA has not conclusively demonstrated the unsafe condition--the cracking of the straps; and, even if there is justification, the 50-hour TIS repetitive inspection interval is too stringent. The FAA does not concur that the strap inspection is unjustified. Based on FAA and Fairchild analysis, loads are shifted to other structures such as the straps when the upper wing skin cracks. Even though the strap carries more load, a crack will not necessarily immediately develop, but may initiate and then propagate slowly (fatigue) because of the additional load in this structural area. For these reasons, the FAA has determined that the strap inspection is needed, but at intervals of 150 hours TIS instead of 50 hours TIS. The proposal has been changed accordingly.

Another commenter, Fairchild Aircraft, recommends the followingchanges to the proposal:

Change the report of "repeated bending of the wing during service" that is contained in the preamble to "reports of wing skin cracking because of repeated bending of the wing during service". The FAA concurs, and has changed the proposal accordingly;

Change the reference of the inspection area for cracks in the proposal from "the lower edge of the nacelle and battery box" to "the top aft outboard corner of the battery box". The FAA concurs and has revised paragraphs (a) and (b)(1) of the proposal accordingly;

Incorporate Fairchild SB 226-57-018, Issued: January 28, 1993, Revised: October 25, 1993 (pages 1 through 3) into the proposal. The FAA concurs and has revised the AD accordingly. This service information revision only includes editorial corrections and does not impose any additional burden of U.S. operators of the affected airplanes; and

Include additional Approved Repair Procedure (ARP) and Limited Approved Repair (LAR) documents and make provisions for the inclusion of future LAR's and ARP's that may be issued. The FAA concurs and has revised NOTE 2 of the proposal as follows:

"Certain Limited Approve Repair (LAR) and Approved Repair Procedure (ARP) documents issued by Fairchild Aircraft specify procedures for accomplishing the same modification referenced in paragraphs (b)(2), (c)(1)(ii), and (c)(2)(ii). Check with the Fort Worth Airplane Certification Office at the address presented in paragraph (e) of this AD to find out which LAR's and ARP's are considered "unless already accomplished" as they relate to this AD."

A third commenter states that the FAA incorrectly estimates the cost impact that the proposed AD would have on U.S. operators of the affected airplanes. This commenter explains that the FAA's cost analysis figure of $42,680 for the entire fleet does not take into account (1) the cost of repetitive inspections; (2) the cost of dye penetrant inspections when the wing skin is found cracked; nor (3) the cost of incorporating the inspection-terminating modification. The FAA concurs that this figure is based only on a one-time visual inspection of the wing skin, as was explained in the cost analysis section of the proposal. The FAA has no way of determining how many airplanes would have cracked wing skins, or how many repetitive inspections each affected airplane would incur. The cost of the modification is extremely labor intensive (100 workhours), a reason why the FAA determined to make it optional until a crack is found in the spar straps. The proposal is unchanged as a result of this comment.

This same commenter states that the modification referenced in the service bulletins is "extreme overkill" because the amount and locations of rivets that require removal creates a potential for additional damage and weakening of the area. The FAA does not concur. Fairchild Aircraft and many operators have already accomplished this modification and the FAA has received no reports of weakening or damage occurring in the affected area. The proposed AD is unchanged as a result of this comment.

After careful review of all available information including the comments referenced above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for the wording changes described above, the incorporation of the revised service information, and minor editorial corrections. The FAA has determined that these minor changes and corrections will not change the meaning of the AD nor add any additional burden upon the public than was already proposed.

The FAA estimates that 776 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 1 workhour per airplane to accomplish the required visual inspection of the wing skin on both wings, and that the average labor rate is approximately $55 an hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $42,680. This figure does not include the cost of any dye penetrant inspections of the spar strap that could be required if the wing skin is found cracked, nor does it include the cost of the wing skin modification or the repetitive inspections. The optional modification would terminate the need for the repetitive inspection requirement. The figure above is based upon the assumption that no affected airplane owner/operator has accomplished this inspection-terminating modification.

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 14 CFR part 39 of the Federal Aviation Regulations as follows:

PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

Section 39.13 - [AMENDED]
2. Section 39.13 is amended by adding the following new AD to read as follows:

Service information that applies to this AD may be obtained from Fairchild Aircraft, P.O. Box 790490, San Antonio, Texas 78279-0490; telephone (512) 824-9421. This information may also be examined at the Federal Aviation Administration (FAA), Central Region, Office of the Assistant Chief Counsel, 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.

Mr. Hung Viet Nguyen, Aerospace Engineer, FAA, Airplane Certification Office, 2601 Meacham Boulevard, Fort Worth, Texas 76137-0150; telephone (817) 222-5150; facsimile (817) 222-5959.