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Proposed Rule

Airworthiness Directives; Ayres Corporation S2R Series and Model 600 S2D Airplanes

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Information about this document as published in the Federal Register.

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Start Preamble Start Printed Page 7789

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Supplemental notice of proposed rulemaking (NPRM); Reopening of the comment period.

SUMMARY:

This document proposes to revise an earlier proposed airworthiness directive (AD) that the Federal Aviation Administration (FAA) issued against Ayres Corporation (Ayres) S2R series and Model 600 S2D airplanes. The earlier proposed rule would supersede the existing AD with a new AD that would require you to repetitively inspect the 1/4-inch and 5/16-inch bolt hole areas on the lower spar caps for fatigue cracking, replace any lower spar cap where fatigue cracking is found, and report any fatigue cracking. The existing AD was the result of an accident of an Ayres S2R series airplane where the wing separated from the airplane in flight. Based upon our continuous evaluation of this situation, we are making minor changes to the most recent proposal; specifically regrouping the affected airplanes into six groups, adjusting the repetitive inspection intervals, providing alternatives for inspection methods, and including modification alternatives to replacing the spar cap. By reopening the comment period, we are allowing you the opportunity to comment on these changes. The actions specified by the proposed AD are intended to detect and correct fatigue cracking of the lower spar caps, which could result in the wing separating from the airplane with consequent loss of control of the airplane.

DATES:

The FAA must receive any comments on the proposed rule on or before April 10, 2000.

ADDRESSES:

Submit comments in triplicate to the FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 98-CE-56-AD, 901 Locust, Room 506, Kansas City, Missouri 64106.

You may get the service information referenced in the proposed AD from the Ayres Corporation, P.O. Box 3090, One Rockwell Avenue, Albany, Georgia 31706-3090. You may examine this information at the Rules Docket at the address above.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Satish Lall, Aerospace Engineer, FAA, Atlanta Aircraft Certification Office, One Crown Center, 1895 Phoenix Boulevard, Suite 450, Atlanta, Georgia 30349; telephone: (770) 703-6082; facsimile: (770) 703-6097.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites comments on this rule. You may submit whatever written data, views, or arguments you choose. You need to include the rule's docket number and submit your comments in triplicate to the address specified under the caption ADDRESSES. The FAA will consider all comments received on or before the closing date. We may amend the proposed rule in light of comments received. Factual information that supports your ideas and suggestions is extremely helpful in evaluating the effectiveness of the proposed AD action and determining whether we need to take additional rulemaking action.

The FAA is re-examining the writing style we currently use in regulatory documents, in response to the Presidential memorandum of June 1, 1998. That memorandum requires federal agencies to communicate more clearly with the public. We are interested in your comments on whether the style of this document is clearer, and any other suggestions you might have to improve the clarity of FAA communications that affect you. You can get more information about the Presidential memorandum and the plain language initiative at http://www.plainlanguage.gov.

The FAA specifically invites comments on the overall regulatory, economic, environmental, and energy aspects of the proposed rule that might suggest a need to modify the rule. You may examine all comments we receive before and after the closing date of the rule in the Rules Docket. We will file a report in the Rules Docket that summarizes each FAA contact with the public that concerns the substantive parts of the proposed AD.

If you want us to acknowledge the receipt of your comments, you must include a self-addressed, stamped postcard. On the postcard, write “Comments to Docket No. 98-CE-56-AD.” We will date stamp and mail the postcard back to you.

Discussion

Has the FAA taken any action to this point? Yes. An accident on an Ayres S2R series airplane where the wing separated from the airplane in flight caused the FAA to issue AD 97-17-03, Amendment 39-10195 (62 FR 43296, August 18, 1997). AD 97-17-03 currently requires you to accomplish the following:

—Inspect the 1/4-inch and 5/16-inch bolt hole areas on the lower spar caps for fatigue cracking;

—Replace any lower spar cap where fatigue cracking is found; and

—Report any fatigue cracking to the FAA.

Investigation of all resources available to the FAA at the time of the accident showed nine occurrences of fatigue cracking in the lower spar caps of Ayres S2R airplanes, specifically emanating from the 1/4-inch and 5/16-inch bolt holes. Investigation of the above-referenced accident revealed that the cause can be attributed to fatigue cracks emanating from the 1/4-inch and 5/16-inch bolt holes in the lower spar caps. Because the Ayres Model 600 S2D airplanes have a similar type design to that of the S2R series airplanes, they were included in the Applicability of AD 97-17-03.

Data indicates that the fatigue cracks on these Ayres S2R series airplanes become detectable at different times based upon the type of engines and design of the airplane. With this in mind, the FAA categorized these airplanes into three groups for the Applicability of AD 97-17-03.

Since issuing AD 97-17-03, we received data specifying 29 additional occurrences of fatigue cracks found in the lower spar caps of Ayres S2R and Model 600 S2D airplanes. The data from Start Printed Page 7790these occurrences indicate the following:

—Several of these occurrences involved airplanes that had not accumulated enough hours to require the initial inspection of AD 97-17-03;

—Detectable cracks could still develop after the initial inspection on the affected airplanes; and

—Ayres has manufactured additional airplanes that have a similar type design to that of the airplanes affected by AD 97-17-03. The existing AD should also cover these airplanes.

To address the above areas, the FAA issued a notice of proposed rulemaking (NPRM) to supersede AD 97-17-03. This NPRM was published in the Federal Register on January 13, 1999 (64 FR 2157). The NPRM proposed to supersede AD 97-17-03 with a new AD that would:

—Retain the inspection and replacement (if necessary) requirements of the lower spar caps that are currently required in AD 97-17-03;

—Make these inspections repetitive;

—Add additional airplanes to the Applicability of the AD;

—Change the initial compliance time for all airplanes; and

—Arrange the affected airplanes into four groups instead of three based on usage and configurations.

Was the public invited to comment on the NPRM? Yes. Interested persons were afforded an opportunity to participate in the making of the amendment. A summary of the comments and the FAA's responses follow.

Comment Issue No. 1: Certain Repetitive Inspection Intervals Too Long

What are the commenters' concerns? Two commenters question why the FAA would allow longer repetitive inspection intervals for airplanes with cold working done on the bolt holes. One commenter questions why longer repetitive inspection intervals are allowed for airplanes with the big butterfly plates (Ayres part numbers 20211-9/-11) installed. The commenters specify the following:

—One commenter bases the comment on cracks found on an airplane where cold working was previously accomplished on the bolt holes. The cracks were found 527 hours time-in-service (TIS) after the cold working and the previous inspection.

—The other commenter states that installing the big butterfly plates would not significantly lower the stress levels in the spar cap and would not delay crack initiation and growth. The commenter also has information that cracks have occurred on airplanes within 500 hours TIS after cold working the bolt holes. The commenter is concerned that corrosion pitting and other defects on the bolt hole inner surface are not adequately removed prior to cold working and that this reduces the effectiveness of cold working the bolt holes.

What is the FAA's response to the concern? We have evaluated the information received to date, including the above comments. Airplanes where bolt holes have been cold worked have not shown a significant reduction in crack growth rates. The safety benefit for airplanes with big butterfly plates installed is not as large as the FAA originally calculated.

Is it necessary to change the proposed AD? Yes. We have adjusted the repetitive inspection intervals for airplanes with the bolt holes cold worked and/or big butterfly plates installed.

Comment Issue No. 2: Change the Applicability Grouping of a Specific Airplane

What are the commenter's concern? One commenter states that the Model S2R-G10 airplane, serial number G10-137, should be categorized as a Group 4 airplane in the Applicability of the proposed AD instead of Group 2. The commenter states that this airplane has big butterfly plates installed and should therefore be included with the other airplanes with big butterfly plates installed.

What is the FAA's response to the concern? We concur that this airplane has big butterfly plates installed and should be re-categorized.

Is it necessary to change the AD? Yes. We have re-categorized the airplanes in the Applicability of the proposed AD into six categories instead of four. This re-categorization allows the FAA to structure the repetitive inspection intervals to coincide with the specific airplane configuration.

Comment Issue No. 3: Require Ultrasonic Inspections

What is the commenter's concern? One commenter recommends using ultrasonic inspection techniques instead of utilizing the magnetic particle method. The commenter states that the magnetic particle method could be used as a final check if a crack is indicated while using the ultrasonic method. This commenter states that, while utilizing the magnetic particle inspection method, damage to the bolt holes can occur during removal and reassembly of the lower splice fitting. Ultrasonic inspections do not require removing the lower splice fitting.

What is the FAA's response to the concern? The FAA concurs that damage can occur when the lower splice fitting is removed and reassembled while accomplishing a magnetic particle inspection. We included a “CAUTION” statement in the NPRM to instruct that the wings must be firmly supported during the inspection to prevent movement of the spar caps when the splice blocks are removed. This allows easier realignment of the splice block holes and the holes in the spar cap for bolt insertion. We are not eliminating the option of using magnetic particle methods because the equipment used in this method is the most readily available in the field.

Is it necessary to change the AD? Yes. We have included different inspection methods as options to accomplishing the actions of the proposed AD. This includes ultrasonic and magnetic particle methods.

Comment Issue No. 4: Ream the 1/4-inch Bolt Holes to 5/16 Inches Diameter

What is the commenter's concern? One commenter recommends that the FAA require the 1/4-inch bolt holes be reamed to 5/16 inches diameter. This commenter states that this will remove any damage caused by previous removal and reassembly of the splice fitting.

What is the FAA's response to the concern? The FAA has approved reaming the 1/4-inch bolt holes to 5/16 inches through the procedures included in Ayres Custom Kit No. CK-AG-29, dated December 23, 1997. We have determined that allowing this as an option is more appropriate than requiring it on all affected airplanes.

Is it necessary to change the AD? No.

Comment Issue No. 5: Require a Hardness Test of All Spar Caps

What is the commenter's concern? One commenter recommends a one-time Rockwell hardness test of all spar caps as specified in National Transportation Safety Board (NTSB) Report No. 98-2. This report specifies that the spar cap on the accident aircraft (reason for the initial AD action on this subject) did not meet the strength specifications for the type of material.

What is the FAA's response to the concern? The FAA has determined that all the spars, including the ones installed on the accident aircraft, have adequate static strength. No Rockwell hardness tests are required. Start Printed Page 7791

Is it necessary to change the AD? No

The FAA's Determination and Followup Action

What have we decided? After careful review of all available information related to the subject presented above, including the above-referenced comments, the FAA has determined that:

—The changes to the proposed AD as described in the above comment disposition should be incorporated; and

—AD action should be taken to incorporate these changes to continue to detect and correct fatigue cracking of the lower spar caps, which could result in the wing separating from the airplane with consequent loss of control of the airplane.

What is our next action? Since the changes propose actions that go beyond the scope of what was already proposed, the FAA is reopening the comment period to allow the public additional time to comment on the proposed AD.

Cost Impact

How many airplanes does the proposed AD impact? The FAA estimates that 1,000 airplanes in the U.S. registry would be affected by the proposed AD.

What is the cost impact of the initial inspection on owners/operators of the affected airplanes? We estimate that it would take approximately 3 workhours per airplane to accomplish the proposed initial inspection, and that the average labor rate is approximately $60 an hour. Parts to accomplish the proposed initial inspection cost approximately $417 per airplane. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $597,000, or $597 per airplane.

What about the cost of repetitive inspections and possible repairs and replacements? The figures above only take into account the cost of the proposed initial inspection and do not take into account the cost of proposed repetitive inspections. We have no way of determining how many repetitive inspections each owner/operator of the affected airplanes would incur. These figures are based upon the presumption that no affected airplane operator has accomplished the proposed inspection, and does not take into account the cost for replacement if a crack is found. We have no way of determining the number of wing spar caps that may need to be replaced based upon the results of the proposed inspections.

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposed rule would not have federalism implications under Executive Order 13132.

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) if promulgated, 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 draft regulatory evaluation prepared for this action has been placed in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

Start Part

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[Amended]

2. Section 39.13 is amended by removing Airworthiness Directive (AD) 97-17-03, Amendment 39-10105 (62 FR 43926, August 18, 1997), and by adding a new AD to read as follows:

Ayres Corporation: Docket No. 98-CE-56-AD Supersedes AD 97-17-03, Amendment 39-10105.

(a) What airplanes are affected by this AD? Airplanes with the following model and serial number (S/N) designations with or without a -DC or -X suffix, certificated in any category:

Group 1 Airplanes

ModelSerial Nos.
S-2R5000R through 5099R, except 5010R, 5031R, 5038R, 5047R, and 5085R.
SR-R1820R1820-001 through R1820-035.
S2R-T346000R through 6049R, T34-001 through T34-143, T34-145, T34-147 through T34-167, T34-171, T34-180, and T34-181.*
S2R-T15T15-001 through T15-033.**
S2R-G1 G1-101 through G1-106.
* The serial numbers of the Model S2R-T34 airplanes could incorporate T34-XXX, T36-XXX, T41-XXX, or T42-XXX. This AD applies to all of these serial number designations as they are all Model S2R-T34 airplanes.
** The serial numbers of the Model S2R-T15 airplanes could incorporate T15-XXX and T27-XXX. This AD applies to both of these serial number designations as they are both Model S2R-T15 airplanes.

Group 2 Airplanes

ModelSerial Nos.
S2R-R1820R1820-036.
S2R-T65T65-001 through T65-017.
S2RHG-T65T65-002 through T65-017.
S2R-T34T34-144, T34-146, T34-168, T34-169, T34-172 through T34-179, and T34-189 through T34-232. And T34-234.*
S2R-T45T45-001 through T45-014.
S2R-G6G6-101 through G6-147.
S2R-G10G10-101 through G10-136, G10-138, G10-140, and G10-141.
Start Printed Page 7792
S2R-G5G5-101 through G5-105.
* The serial numbers of the Model S2R-T34 airplanes could incorporate T34-XXX, T36-XXX, T41-XXX, or T42-XXX. This AD applies to all of these serial number designations as they are all Model S2R-T34 airplanes.

Group 3 Airplanes*

ModelSerial Nos.
600 S2DAll serial numbers beginning with 600-1311D.
S-2R1380R and 1416R through 4999R.
S2R-R1340R1340-001 through R1340-035.
S2R-R3SR3S-001 through R3S-011.
S2R-T11T11-001 through T11-005.
* Any Group 3 airplane that has been modified with a hopper of a capacity over 410 gallons a piston engine greater than 600 horsepower or any gas turbine engine makes the airplane a Group 1 airplane for the purposes of this AD. The owner/operator must inspect the airplane at the Group 1 compliance time specified in this AD.

Group 4 Airplanes

ModelSerial Nos.
S2R-T34T34-225, T34-236, T34-237, and T34-238.*
S2R-G1G1-107, G1-108, and G1-109.
S2R-G10G10-137, G10-139, and G10-142.
* The serial numbers of the Model S2R-T34 airplanes could incorporate T34-XXX, T36-XXX, T41-XXX, or T42-XXX. This AD applies to all of these serial number designations as they are all Model S2R-T34 airplanes.

Group 5 Airplanes

ModelSerial Nos.
S2R-T34T34-239 through T34-266.*
S2RHG-T34T34HG-102.
S2R-T15T15-034 through T15-040.**
S2R-T45T45-015.
S2R-G1G1-110 through G1-114.
S2R-G6G6-148 through G6-151.
S2R-G10G10-143 through G10-160.
* The serial numbers of the Model S2R-T34 airplanes could incorporate T34-XXX, T36-XXX, T41-XXX, or T42-XXX. This AD applies to all of these serial number designations as they are all Model S2R-T34 airplanes.
** The serial numbers of the Model S2R-T15 airplanes could incorporate T15-XXX and T27-XXX. This AD applies to both of these serial designations as they are both Model S2R-T15 airplanes.

Group 6 Airplanes

ModelSerial Nos.
S2R5010R, 5031R, 5038R, 5047R, and 5085R.

(b) Who must comply with this AD? Anyone who wishes to operate any of the above airplanes on the U.S. Register.

(c) What problem does this AD address? The actions specified by the proposed AD are intended to detect and correct fatigue cracking of the lower spar caps. This could result in the wing separating from the airplane with consequent loss of control of the airplane.

(d) What actions must I accomplish to address this problem? To address this problem, you must accomplish the following:

(1) Repetitively inspect, using magnetic particle, ultrasonic, or eddy current procedures, the 1/4-inch and 5/16-inch bolt hole areas on each lower spar cap for fatigue cracking. Reference paragraph (e)(3) and (e)(4) of this AD (including all subparagraphs) to obtain the initial and repetitive inspection compliance times.

(i) The cracks may emanate from the bolt hole on the face of the spar cap or they may occur in the shaft of the hole.

(ii) You must inspect both of these areas.

(2) If any cracking is found during any inspection required by this AD, you must accomplish the following:

(i) Use the cold work process to ream out small cracks as defined in Ayres Service Bulletin No. SB-AG-39, dated September 17, 1996; or replace the affected spar cap in accordance with the maintenance manual; or ream the 1/4-inch bolt holes to 5/16 inches diameter as defined in Part I of Ayres Custom Kit No. CK-AG-29, dated December 23, 1997; and

(ii) Submit a report of inspection findings to the Manager, Atlanta ACO, One Crown Center, 1895 Phoenix Boulevard, Suite 450, Atlanta, Georgia 30349; facsimile: (770) 703-6097. You must include the airplane serial number and engine model number; the total number of flight hours on the lower spar cap that is cracked; time on the spar cap since last inspection, if applicable; and the type of inspection used for the last inspection. Indicate if cold working has been accomplished or modifications incorporated such as installation of big butterfly plates. Include the time on the spar cap when the cold working or modifications were accomplished. Indicate which bolt hole is Start Printed Page 7793cracked and the length of the crack. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.

(e) What is the compliance time of this AD? The compliance times for each of the actions of this AD are as follows:

(1) Any required repair or replacement: Prior to further flight after the inspection where the crack(s) was/were found.

(2) Reporting requirement:

(i) Submit the report within 10 days after finding any crack(s) during any inspection required by this AD.

(ii) For airplanes where cracking was found during any inspection accomplished in accordance with AD 97-17-03, which is superseded by this AD; or by AD 97-13-11, which was superseded by AD 97-17-03, submit the report within 10 days after the effective date of this AD, unless already accomplished.

(3) Initial Inspection: The following is for the initial inspections required by this AD. The affected airplanes are categorized into six different groups.

(i) Group 1 Airplanes: Required upon the accumulation of 2,000 hours time-in-service (TIS) on each lower spar cap or within 50 flight hours after the effective date of this AD, whichever occurs later, unless already accomplished (compliance with AD 97-17-03 or AD 97-13-11).

(ii) Group 2 Airplanes: Required upon the accumulation of 2,200 hours TIS on each lower spar cap or within 50 flight hours after the effective date of this AD, whichever occur later, unless already accomplished (compliance with AD 97-17-03 or AD 97-13-11).

(iii) Group 3 Airplanes: Required upon the accumulation of 6,400 hours TIS on each lower spar cap or within 50 flight hours after the effective date of this AD, whichever occurs later, unless already accomplished (compliance with AD 97-17-03 or AD 97-13-11).

(iv) Group 4 Airplanes: Required upon the accumulation of 2,500 hours TIS on each lower spar cap or within 50 flight hours after the effective date of this AD, whichever occurs later, unless already accomplished (compliance with AD 97-17-03 or AD 97-13-11).

(v) Group 5 Airplanes: Required upon the accumulation of 6,200 hours TIS on each lower spar cap or within 50 flight hours after the effective date of this AD, whichever occurs later, unless already accomplished (compliance with AD 97-17-03 or AD 97-13-11).

(vi) Group 6 Airplanes: As presented below.

(A) For S/N 5010R: Required upon the accumulation of 5,530 hours TIS on each lower spar cap or within the next 50 hours TIS after the effective date of this AD, whichever occurs later.

(B) For S/N 5038R: Required upon the accumulation of 5,900 hours TIS on each lower spar cap or within the next 50 hours TIS after the effective date of this AD, whichever occurs later.

(C) For S/N's 5031R and 5047R: Required upon the accumulation of 6,400 hours TIS on each lower spar cap or within the next 50 hours TIS after the effective date of this AD, whichever occurs later.

(D) For S/N 5085R: Required upon the accumulation of 6,290 hours TIS on each lower spar cap or within the next 50 hours TIS after the effective date of this AD, whichever occurs later.

(4) Repetitive Inspections: The following chart gives the required repetitive inspection intervals based on the work performed and the method of inspection utilized. Each time is hours TIS intervals after the last inspection:

Work previously performedMagnetic particleUltrasonicEddy current
No Cracks with optional cold work accomplished per SB-AG-39; or optional 1/4-inch bolt hole reamed to 5/16 inches diameter per CK-AG-29, Part I, or previous Alternative Methods of Compliance.**500 hours TIS550 hours TIS700 hours TIS.
No Cracks with optional cold work accomplished per SB-AG-39 or optional 1/4-inch bolt hole reamed to 5/16 inches diameter per CK-AG-29, Part I, or previous Alternative Methods of Compliance**; and butterfly plates, part number (P/N) 20211-09 and P/N 20211-11, installed per CK-AG-29, Part II.***900 hours TIS950 hours TIS1,250 hours with TIS.
*Aircraft S/N's T45-007DC and T45-10DC had modified splice block assemblies installed at Ayres (Ayres/Kaplan Assembly No. 88-251) and must still follow the repetitive inspection intervals listed here.
**If a crack is found, the reaming associated with the cold work process may remove a crack if it is small enough. Some aircraft owners/operators were issued alternative methods of compliance with AD 97-17-03 to ream the 1/4-inch bolt hole to 5/16 inches diameter to remove small cracks. Ayres CK-AG-29, Part I, also provides procedures to ream the 1/4-inch bolt hole to 5/16 inches diameter. If you use either of these two methods to remove cracks and the airplane is reinspected immediately with no cracks found, you may continue to follow the repetitive inspection intervals listed above.
***Group 4 and Group 5 airplanes had the butterfly plates installed at the factory and may follow this repetitive inspection interval.

(f) What procedures must I use to accomplish the actions required in this AD?

(1) Inspections:

(i) For the magnetic particle inspection, utilize the procedures contained in Ayres Service Bulletin No. SB-AG-39, dated September 17, 1996. Use only sections titled “Inspection Accomplishment Instructions” and “Lower Splice Fitting Removal and Installation Instructions.” You must follow American Society for Testing Materials (ASTM) E1444-94A, using wet particles meeting the requirements of the Society for Automotive Engineers (SAE) AMS 3046. CAUTION: You must firmly support the wings during the inspection to prevent movement of the spar caps when the splice blocks are removed. This will allow easier realignment of the splice block holes and the holes in the spar cap for bolt insertion.

(ii) The FAA must approve ultrasonic or eddy current inspection procedures. To obtain FAA approval, you must send your proposed procedure to the Manager, Atlanta Aircraft Certification (ACO), One Crown Center, 1895 Phoenix Boulevard, Suite 450, Atlanta, Georgia 30349. You are not required to remove the splice block for either the ultrasonic or eddy current inspections, unless corrosion is visible.

(iii) All inspections required by this AD must be accomplished by a Level 2 or Level 3 inspector certified for that inspection method using the guidelines established by the American Society for Nondestructive Testing or MIL-STD-410.

(2) Repair: Utilize the procedures contained in Ayres Service Bulletin No. SB-AG-39, dated September 17, 1996; or in Part I of Ayres Custom Kit No. CK-AG-29, dated December 23, 1997 if necessary to remove small cracks. You must then immediately re-inspect and continue to accomplish the repetitive inspections.

(3) Replacement: Utilize the procedures contained in the maintenance manual.

(g) Can I comply with this AD in any other way? Yes.

(1) You may use an alternative method of compliance or adjust the compliance time if:

(i) Your alternative method of compliance provides an equivalent level of safety; and

(ii) The Manager, Atlanta Aircraft Certification Office, approves your alternative. Submit your request through an FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager.

(2) 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 (g)(1) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by Start Printed Page 7794this AD; and, if you have not eliminated the unsafe condition, specific actions you propose to address it.

(3) Alternative methods of compliance approved in accordance with AD 97-17-03, which is superseded by this AD; or in accordance with AD 97-13-11, which was superseded by AD 97-17-03, are approved as alternative methods of compliance with this AD, unless otherwise noted in this AD.

(h) Where can I get information about any already-approved alternative methods of compliance? Contact the Atlanta ACO, One Crown Center, 1895 Phoenix Boulevard, Suite 450, Atlanta, Georgia 303496; telephone: (770) 703-6082; facsimile: (770) 703-6097.

(i) What if I need to fly the airplane to another location to comply with this AD? The FAA can issue a special flight permit under sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate your airplane to a location where you can accomplish the requirements of this AD, provided the following is followed:

(1) The hopper is empty.

(2) Vne is reduced to 126 miles per hour (109 knots).

(3) Flight into known turbulence is prohibited.

(j) You may obtain copies of the documents referenced in this document from the Ayres Corporation, P.O. Box 3090, One Rockwell Avenue, Albany, Georgia 31706-3090. You may examine these documents at the FAA, Central Region, Office of the Regional Counsel, 901 Locust, Room 506, Kansas City, Missouri 64106.

(k) This amendment supersedes AD 97-17-03, Amendment 39-10105.

Start Signature

Issued in Kansas City, Missouri, on February 8, 2000.

Michael K. Dahl,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. 00-3623 Filed 2-15-00; 8:45 am]

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