[Federal Register Volume 71, Number 64 (Tuesday, April 4, 2006)]
[Rules and Regulations]
[Pages 16691-16696]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-3162]



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  Federal Register / Vol. 71, No. 64 / Tuesday, April 4, 2006 / Rules 
and Regulations  

[[Page 16691]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-23649; Directorate Identifier 2006-CE-08-AD; 
Amendment 39-14542; AD 2006-07-15]
RIN 2120-AA64


Airworthiness Directives; Thrush Aircraft, Inc. Model 600 S2D and 
S2R (S-2R) Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

-----------------------------------------------------------------------

SUMMARY: The FAA is adopting a new airworthiness directive (AD) to 
supersede AD 2003-07-01, which applies to certain Thrush Aircraft, Inc. 
Model 600 S2D and S2R (S-2R) series airplanes (type certificate 
previously held by Quality Aerospace, Inc. and Ayres Corporation). AD 
2003-07-01 currently requires you to repetitively inspect the \1/4\-
inch and \5/16\-inch bolt hole areas on the lower wing spar caps for 
fatigue cracking; replace or repair any lower wing spar cap where 
fatigue cracking is found; and report any fatigue cracking found. This 
AD is the result of the analysis of data from 112 cracks found in the 
last 8 years on similar design Model 600 S2D and S2R (S-2R) series 
airplanes, and FAA's determination that an immediate initial inspection 
and more frequent repetitive inspections are necessary to address the 
unsafe condition for certain airplanes. Consequently, this AD would 
require you to increase the frequency of the repetitive inspections on 
Groups 1, 2, 3, and 6 airplanes; and decrease the hours time-in-service 
(TIS) for the initial inspection on Group 2 airplanes. We are issuing 
this AD to prevent lower wing spar cap failure caused by undetected 
fatigue cracks. Such failure could result in loss of a wing with 
consequent loss of airplane control.

DATES: This AD becomes effective on April 18, 2006.
    As of July 25, 2000 (65 FR 36055), the Director of the Federal 
Register previously approved the incorporation by reference of Ayres 
Corporation Service Bulletin No. SB-AG-39, dated September 17, 1996; 
and Ayres Corporation Custom Kit No. CK-AG-29, dated December 23, 1997.
    As of May 20, 2003 (68 FR 15653), the Director of the Federal 
Register previously approved the incorporation by reference of Quality 
Aerospace, Inc. Custom Kit No. CK-AG-30, dated December 6, 2001, in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
    We must receive any comments on this AD by May 16, 2006.

ADDRESSES: Use one of the following to submit comments on this AD:
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-001.
     Fax: 1-202-493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    To get the service information identified in this proposed AD, 
contact Thrush Aircraft, Inc. at 300 Old Pretoria Road, PO Box 3149, 
Albany, Georgia 31706-3149. You can also find service information on 
their Web site at http://www.thrushaircraft.com.
    To view the comments to this AD, go to http://dms.dot.gov. The 
docket number is FAA-2006-23649; Directorate Identifier 2006-CE-08-AD.
    For Further Information Contact One of the Following:


--Cindy Lorenzen, Aerospace Engineer, ACE-115A, Atlanta Aircraft 
Certification Office, One Crown Center, 1895 Phoenix Blvd., Suite 450, 
Atlanta, Georgia 30349; telephone: (770) 703-6078; facsimile: (770) 
703-6097; e-mail: [email protected]; or
--Mike Cann, Aerospace Engineer, ACE-117A, Atlanta Aircraft 
Certification Office, One Crown Center, 1895 Phoenix Blvd., Suite 450, 
Atlanta, Georgia 30349; telephone: (770) 703-6038; facsimile: (770) 
703-6097; e-mail: [email protected].

SUPPLEMENTARY INFORMATION:

History of AD Actions

    An accident on a Thrush S2R series airplane (type certificate 
previously held by Quality Aerospace, Inc. and Ayres Corporation), 
where the wing separated from the airplane in flight, caused us to 
issue AD 97-13-11, Amendment 39-10071 (62 FR 36978, July 10, 1997). AD 
97-13-11 required you to do the following:

--Inspect the \1/4\-inch and \5/16\-inch bolt hole areas on the lower 
wing spar caps for fatigue cracking;
--Replace any lower wing spar cap where fatigue cracking is found; and
--Report any fatigue cracking to FAA.

    AD 97-17-03, Amendment 39-10195 (62 FR 43926, August 18, 1997) 
superseded AD 97-13-11. AD 97-13-11 incorrectly referenced the Model 
S2R-R1340 airplanes as Model S2R-1340R. AD 97-17-03 corrected the model 
designation and retained the actions of AD 97-13-11.
    AD 2000-11-16, Amendment 39-11764 (65 FR 36055, June 7, 2000) 
superseded AD 97-17-03. AD 2000-11-16 made the inspections required in 
AD 97-17-03 repetitive, added airplanes to the applicability of the AD, 
changed the initial compliance time for all airplanes, and arranged the 
affected airplanes into six groups based on usage and configuration. AD 
2000-11-16 required you to do the following:

--Repetitively inspect the \1/4\-inch and \5/16\-inch bolt hole areas 
on the lower wing spar caps for fatigue cracking;
--Replace or repair any lower wing spar cap where fatigue cracking is 
found; and
--Report any fatigue cracking to FAA.

    AD 2003-07-01, Amendment 39-13097 (68 FR 15653, April 1, 2003) 
superseded AD 2000-11-16. AD 2003-07-01 added some airplanes that were 
manufactured with a similar design to the applicability table and added 
a third repair option.

[[Page 16692]]

Recent Events That Initiated This Current AD Action

    AD 2003-07-01 required submitting reports to FAA when any crack was 
found on the affected airplanes. Recent FAA analysis of data from those 
reports and other historical and statistical data indicate that the 
current AD inspections are not completely addressing the unsafe 
condition. Specifically, the data indicate a risk that some airplanes 
in the Thrush fleet may currently have cracks. The airplanes with 
cracks may be unable to meet ultimate strength requirements.
    The repetitive inspection interval required by AD 2003-07-01 was 
designed to give owners/operators two opportunities to detect a crack 
before the critical crack length is reached. The high rate of cracking 
in the fleet combined with the industry standard of a 90-percent 
probability of detection with the inspection methods used means that 
eventually an inspection will not find an existing crack. A completely 
severed spar cap was found on one of the affected airplanes. Analysis 
indicates a crack existed during the last two repetitive inspections of 
that spar cap, but the crack was undetected by the inspections. 
Fortunately, the wing remained intact until the crack was found.
    This in-service incident correlates with other historical 
probability data that indicate there may be cracks in other lower wing 
spar caps in the fleet now, and those cracks may go undetected with 
current inspection intervals. The FAA used a probability approach when 
analyzing the risks from data obtained from reports of 112 lower wing 
spar cap cracks found on Model 600 S2D and S2R (S-2R) series airplanes 
since 1997. This analysis indicates there is an ever-increasing risk of 
another crack being missed during an inspection.
    To increase the chances of detecting a crack in the lower wing spar 
cap prior to the crack reaching critical length, we are increasing the 
frequency of the repetitive inspections on Groups 1, 2, 3, and 6 
airplanes and decreasing the hours TIS for the initial inspection on 
Group 2 airplanes. These actions are necessary to ensure the continued 
airworthiness of Groups 1, 2, 3, and 6 airplanes. There has been one 
crack reported on Groups 4 and 5 airplanes; however, this is not enough 
statistical data to show an increasing risk for these airplanes at this 
time. Until additional information is obtained, we are not changing the 
initial inspection times or the repetitive inspection intervals for 
Groups 4 and 5 airplanes.
    Wing spar cap failure caused by undetected fatigue cracks could 
result in loss of a wing with consequent loss of airplane control.

Relevant Service Information

    The following service information was included in AD 2003-07-01 and 
will remain in effect for this AD:

--Ayres Corporation Service Bulletin No. SB-AG-39, dated September 17, 
1996;
--Ayres Corporation Custom Kit No. CK-AG-29, dated December 23, 1997; 
and
--Quality Aerospace, Inc. Custom Kit No. CK-AG-30, dated December 6, 
2001.

    The service information includes procedures for:

--Inspecting the \1/4\-inch and \5/16\-inch bolt hole areas on the 
lower wing spar caps for fatigue cracking;
--Reworking the spar cap if a small crack is found in the \1/4\-inch 
spar cap hole;
--Replacing the butterfly center splice plate, part number 20211-3, 
from the aft surface of the wing spar join area; and
--Installing Kaplan splice blocks that repair small cracks in the \1/
4\-inch and \5/16\-inch bolt holes.

FAA's Determination and Requirements of the AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other Thrush 
Aircraft, Inc. Model 600 S2D and S2R (S-2R) series airplanes of the 
same type design. Therefore, we are issuing this AD to prevent lower 
wing spar cap failure caused by undetected fatigue cracks. Such failure 
could result in loss of a wing with consequent loss of airplane 
control.
    This AD supersedes AD 2003-07-01 with a new AD that retains the 
actions of the previous AD, but increases the frequency of the 
repetitive inspections on Groups 1, 2, 3, and 6 airplanes; and 
decreases the hours TIS for the initial inspection on Group 2 
airplanes.
    In preparing this rule, we contacted type clubs and aircraft 
operators to get technical information and information on operational 
and economic impacts. We have included a discussion of information that 
may have influenced this action in the rulemaking docket.
    For any of the affected airplanes that exceed the new repetitive 
inspection interval at the effective date of this AD, the compliance 
times are graduated based on the increasing risk of the airplanes with 
the most hours since their last inspection. Graduated compliance times 
will help alleviate overcrowding at inspection facilities while still 
addressing the increased risk for airplanes that have accumulated the 
most flight hours since the last inspection. We are working with Thrush 
to develop a future terminating action.

Comments Invited

    This AD is a final rule that involves requirements affecting flight 
safety and was not preceded by notice and an opportunity for public 
comment; however, we invite you to submit any written relevant data, 
views, or arguments regarding this AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2006-23649; 
Directorate Identifier 2006-CE-08-AD'' in the subject line of your 
comments. If you want us to acknowledge receipt of your mailed 
comments, send us a self-addressed, stamped postcard with the docket 
number written on it; we will date-stamp your postcard and mail it back 
to you. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify it. If a person contacts us through a 
nonwritten communication, and that contact relates to a substantive 
part of this AD, we will summarize the contact and place the summary in 
the docket. We will consider all comments received by the closing date 
and may amend the AD in light of those comments.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106 describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the agency's authority.
    We are issuing this rulemaking under the authority described in 
subtitle VII, part A, subpart III, section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this AD.

[[Page 16693]]

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will not have a 
substantial direct effect on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government.
    For the reasons discussed above, I certify that this AD:
    1. Is not a ``significant regulatory action'' under Executive Order 
12866;
    2. Is not a ``significant rule'' under the DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979); and
    3. Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    We prepared a summary of the costs to comply with this AD (and 
other information as included in the Regulatory Evaluation) and placed 
it in the AD Docket. You may get a copy of this summary by sending a 
request to us at the address listed under ADDRESSES. Include ``AD 
Docket FAA-2006-23649; Directorate Identifier 2006-CE-08-AD'' in your 
request.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under 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

0
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]

0
2. The FAA amends Sec.  39.13 by removing Airworthiness Directive (AD) 
2003-07-01, Amendment 39-13097 (68 FR 15653, datee April 1, 2003), and 
by adding a new AD to read as follows:

2006-07-15 Thrush Aircraft, Inc. (Type Certificate Previously Held 
by Quality Aerospace, Inc. and Ayres Corporation): Amendment 39-
14542; Docket No. FAA-2006-23649; Directorate Identifier 2006-CE-08-
AD.

Effective Date

    (a) This AD becomes effective on April 18, 2006.

Affected ADs

    (b) The following lists a history of the ADs affected by this AD 
action:
    (1) This AD supersedes AD 2003-07-01; Amendment 39-13097;
    (2) AD 2003-07-01 superseded AD 2000-11-16, Amendment 39-11764;
    (3) AD 2000-11-16 superseded AD 97-17-03, Amendment 39-10195; 
and
    (4) AD 97-17-03 superseded AD 97-13-11, Amendment 39-10071.

Applicability

    (c) This AD affects the following airplane models and serial 
numbers that are certificated in any category. The table also 
identifies the group that each airplane belongs in when determining 
inspection compliance times:

               Table 1.--Applicability and Airplane Groups
------------------------------------------------------------------------
               Model                         Serial Nos.           Group
------------------------------------------------------------------------
(1) S-2R...........................  5000R through 5100R, except       1
                                      5010R, 5031R, 5038R,
                                      5047R, and 5085R.
(2) S2R-G1.........................  G1-101 through G1-106......       1
(3) S2R-R1820......................  R1820-001 through R1820-035       1
(4) S2R-T15........................  T15-001 through T15-033....       1
(5) S2R-T34........................  6000R through 6049R, T34-         1
                                      001 through T34-143, T34-
                                      145, T34-147 through T34-
                                      167, T34-171, T34-180, and
                                      T34-181.
(6) S2R-G10........................  G10-101 through G10-136,          2
                                      G10-138, G10-140, and G10-
                                      141.
(7) S2R-G5.........................  G5-101 through G5-105......       2
(8) S2R-G6.........................  G6-101 through G6-147......       2
(9) S2RHG-T65......................  T65-002 through T65-018....       2
(10) S2R-R1820.....................  R1820-036..................       2
(11) S2R-T34.......................  T34-144, T34-146, T34-168,        2
                                      T34-169, T34-172 through
                                      T34-179, and T34-189
                                      through T34-232, and T34-
                                      234.
(12) S2R-T45.......................  T45-001 through T45-014....       2
(13) S2R-T65.......................  T65-001 through T65-018....       2
(14) 600 S2D.......................  All serial numbers                3
                                      beginning with 600-1311D.
(15) S-2R..........................  1380R, 1416R through 2592R,       3
                                      3000R, and 3002R.
(16) S2R-R1340.....................  R1340-001 through R1340-035       3
(17) S2R-R3S.......................  R3S-001 through R3S-011....       3
(18) S2R-T11.......................  T11-001 through T11-005....       3
(19) S2R-G1........................  G1-107, G1-108, and G1-109.       4
(20) S2R-G10.......................  G10-137, G10-139, and G10-        4
                                      142.
(21) S2R-T34.......................  T34-225, T34-236, T34-237,        4
                                      and T34-238.
(22) S2R-G1........................  G1-110 through G1-115......       5
(23) S2R-G10.......................  G10-143 through G10-165....       5
(24) S2R-G6........................  G6-148 through G6-155......       5
(25) S2RHG-T34.....................  T34HG-102..................       5
(26) S2R-T15.......................  T15-034 through T15-040....       5
(27) S2R-T34.......................  T34-239 through T34-270....       5
(28) S2R-T45.......................  T45-015....................       5
(29) S-2R..........................  5010R, 5031R, 5038R, 5047R,       6
                                      and 5085R.
------------------------------------------------------------------------


    Note 1: The serial numbers of the Model S2R-T15 airplanes could 
incorporate T15-xxx and T27-xxx (xxx is the variable for any of the 
serial numbers beginning with T15- and T27-). This AD applies to 
both of these serial number designations as they are both Model S2R-
T15 airplanes.


    Note 2: The serial numbers of the Model S2R-T34 airplanes could 
incorporate T34-xxx, T36-xxx, T41-xxx, or T42-xxx (xxx is the 
variable for any of the serial numbers beginning with T34-, T36-, 
T41- and

[[Page 16694]]

T42-). This AD applies to all of these serial number designations as 
they are all Model S2R-T34 airplanes.


    Note 3: Any Group 3 airplane that has been modified with a 
hopper of a capacity more than 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. Inspect the airplane 
at the Group 1 compliance time specified in this AD.


    Note 4: Group 6 airplanes were originally manufactured with 
turbine engines, but were converted to radial engines. They are now 
configured identical to Group 3 airplanes.

Unsafe Condition

    (d) This AD is the result of the analysis of data from 112 
cracks found in the last 8 years on similar design Model 600 S2D and 
S2R (S-2R) series airplanes, and FAA's determination that an 
immediate initial inspection and more frequent repetitive 
inspections are necessary to address the unsafe condition for 
certain airplanes. We are issuing this AD to prevent lower wing spar 
cap failure caused by undetected fatigue cracks. Such failure could 
result in loss of a wing with consequent loss of airplane control.

Compliance

    (e) To address the problem, do the following:
    (1) If you have already done an inspection per AD 2003-07-01, 
identify the number of hours time-in-service (TIS) since your last 
inspection per AD 2003-07-01. You will need this to establish the 
inspection interval for next inspection required by this AD.
    (2) Inspect the \1/4\-inch and \5/16\-inch bolt hole areas on 
each wing lower spar cap for fatigue cracking using magnetic 
particle, ultrasonic, or eddy current procedures. If Kaplan splice 
blocks, part number (P/N) 22515-1/-3 or 88-251 per Quality 
Aerospace, Inc. Custom Kit No. CK-AG-30, dated December 6, 2001, are 
installed, inspect the three bolt hole areas on each wing lower spar 
cap for fatigue cracking using magnetic particle, ultrasonic, or 
eddy current procedures. Use the compliance times listed in 
paragraph (e)(3) of this AD for the initial inspection and the 
compliance time listed in paragraphs (e)(5), (e)(6), or (e)(7) of 
this AD for the repetitive inspections. 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. You must inspect both of those areas.
    (i) If using the magnetic particle method for the inspection, 
inspect using the ``Inspection'' portion of the ``Accomplishment 
Instructions'' and ``Lower Splice Fitting Removal and Installation 
Instructions'' in Ayres Corporation Service Bulletin No. SB-AG-39, 
dated September 17, 1996. You must follow American Society for 
Testing and Materials E 1444-01, using wet particles meeting the 
requirements of the Society for Automotive Engineers 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 inspection must be done by or supervised by a Level 2 
or Level 3 inspector certified following the guidelines established 
by the American Society for Nondestructive Testing or MIL-STD-410.
    (iii) If using ultrasonic or eddy current methods for the 
inspection, a procedure must be sent to the FAA, Atlanta Aircraft 
Certification Office (ACO), for approval before doing the 
inspection. Send your proposed procedure to the FAA, Atlanta ACO, 
Attn: Cindy Lorenzen, 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.
    (iv) If you change the inspection method used (magnetic 
particle, ultrasonic, or eddy current), the TIS intervals for 
repetitive inspections are based on the method used for the last 
inspection.
    (3) If airplanes have not reached the threshold for the initial 
inspection required in AD 2003-07-01, AD 2000-11-16, AD 97-17-03, or 
AD 97-13-11, initially inspect following the wing lower spar cap 
hours TIS schedule below or within 50 wing lower spar cap hours TIS 
after April 18, 2006 (the effective date of this AD), whichever 
occurs later:

                      Table 2.--Initial Inspection
------------------------------------------------------------------------
                                          Initially inspect within the
            Airplane  group               following lower wing spar cap
                                                    hours TIS
------------------------------------------------------------------------
(i) Group 1...........................  2,000 hours TIS.
(ii) Group 2..........................  1,400 hours TIS.
(iii) Group 3.........................  6,400 hours TIS.
(iv) Group 4..........................  2,500 hours TIS.
(v) Group 5...........................  6,200 hours TIS.
(vi) Group 6..........................  (A) Serial number (S/N) 5010R:
                                         5,530 hours TIS.
                                        (B) S/N 5038R: 5,900 hours TIS.
                                        (C) S/N 5031R: 6,400 hours TIS.
                                        (D) S/N 5047R: 6,400 hours TIS.
                                        (E) S/N 5085R: 6,290 hours TIS.
------------------------------------------------------------------------

    (4) Airplanes in all groups must meet the following conditions 
before doing the repetitive inspections required in paragraphs 
(e)(5), (e)(6), or (e)(7) of this AD:
    (i) No cracks have been found previously on wing spar;
    (ii) Small cracks have been repaired through cold work (or done 
as an option if never cracked) per SB-AG-39;
    (iii) Small cracks have been repaired by reaming the \1/4\-inch 
bolt hole to \5/16\ inches diameter (or done as an option if never 
cracked) per Ayres Corporation Custom Kit No. CK-AG-29, Part I, 
dated December 23, 1997;
    (iv) Small cracks have been repaired through previous 
alternative methods of compliance (AMOC); or
    (v) Small cracks have been repaired by the installation of 
Kaplan splice blocks, P/N 22515-1/-3 or 88-251 (or done as an option 
if never cracked) per Quality Aerospace, Inc. Custom Kit No. CK-AG-
30, dated December 6, 2001.
    (5) Repetitively inspect Groups 1, 2, 3, and 6 airplanes that do 
not have butterfly plates, P/N 20211-09 and P/N 20211-11, installed 
per Ayres Corporation Custom Kit No. CK-AG-29, Part II, dated 
December 23, 1997, and meet the conditions in paragraph (e)(4) of 
this AD. Follow the wing lower spar cap hours TIS compliance 
schedule below:

          Table 3.--Repetitive Inspections for Airplane Groups 1, 2, 3, and 6 Without Butterfly Plates
----------------------------------------------------------------------------------------------------------------
 When airplanes accumulate the following   Inspect within the following
  hours TIS on the wing lower spar cap,      hours TIS after April 18,    Inspect thereafter at intervals of . .
 since the last inspection required in AD   2006 (the effective date of                     .
               2003-07-01,                           this AD),
----------------------------------------------------------------------------------------------------------------
(i) Magnetic particle inspection.........  ............................  250 hours TIS.
    (A) 450 or more hours................   25 hours TIS...............
    (B) 350 through 449 hours TIS........  50 hours TIS................
    (C) 175 through 349 hours TIS........  75 hours TIS................
    (D) Less than 175 hours TIS..........  upon accumulating 250 hours
                                            TIS.
(ii) Ultrasonic inspection...............  ............................  275 hours TIS.
    (A) 500 or more hours TIS............  25 hours TIS................
    (B) 400 through 499 hours TIS........  50 hours TIS................
    (C) 200 through 399 hours TIS........  75 hours TIS................
    (D) Less than 200 hours TIS..........  upon accumulating 275 hours
                                            TIS.
(iii) Eddy Current inspection............  350 hours TIS...............
    (A) 625 or more hours TIS............  25 hours TIS................
    (B) 500 through 624 hours TIS........  50 hours TIS................
    (C) 275 through 499 hours TIS........  75 hours TIS................

[[Page 16695]]

 
    (D) Less than 275 hours TIS..........  upon accumulating 350 hours
                                            TIS.
----------------------------------------------------------------------------------------------------------------

    (6) Repetitively inspect Groups 1, 2, 3, and 6 airplanes that 
have butterfly plates, P/N 20211-09 and P/N 20211-11, installed per 
Ayres Corporation Custom Kit No. CK-AG-29, Part II, dated December 
23, 1997, and meet the conditions in paragraph (e)(4) of this AD. 
Follow the wing lower spar cap hours TIS compliance schedule below:

                Table 4.--Repetitive Inspections for Groups 1, 2, 3, and 6 With Butterfly Plates
----------------------------------------------------------------------------------------------------------------
 When airplanes accumulate the following   Inspect within the following
  hours TIS on the wing lower spar cap,      hours TIS after April 18,    Inspect thereafter at intervals of . .
 since the last inspection required in AD   2006 (the effective date of                     .
               2003-07-01,                           this AD),
----------------------------------------------------------------------------------------------------------------
(i) Magnetic particle inspection.........  ............................  450 hours TIS.
    (A) 800 or more hours TIS............  25 hours TIS................
    (B) 650 through 799 hours TIS........  50 hours TIS................
    (C) 375 through 649 hours TIS........  75 hours TIS................
    (D) Less than 375 hours TIS..........  upon accumulating 450 hours
                                            TIS.
(ii) Ultrasonic inspection...............  ............................  475 hours TIS.
    (A) 825 or more hours TIS............  25 hours TIS................
    (B) 675 through 824 hours TIS........  50 hours TIS................
    (C) 400 through 674 hours TIS........  75 hours TIS................
    (D) Less than 400 hours TIS..........  upon accumulating 475 hours
                                            TIS.
(iii) Eddy Current inspection............  ............................  625 hours TIS
    (A) 1125 or more hours TIS...........  25 hours TIS................
    (B) 900 through 1124 hours TIS.......  50 hours TIS................
    (C) 550 through 899 hours TIS........  75 hours TIS................
    (D) Less than 550 hours TIS..........  upon accumulating 625 hours
                                            TIS.
----------------------------------------------------------------------------------------------------------------

    (7) Repetitively inspect Groups 4 and 5 airplanes that meet the 
conditions in paragraph (e)(4) of this AD. Follow the wing lower 
spar cap hours TIS compliance schedule below:

           Table 5.--Repetitive Inspection for Groups 4 and 5
------------------------------------------------------------------------
  When using the following inspection        Repetitively inspect at
                methods,                        intervals of . . .
------------------------------------------------------------------------
(i) Magnetic particle inspection.......  900 hours TIS.
(ii) Ultrasonic inspection.............  950 hours TIS.
(iii) Eddy current inspection..........  1,250 hours TIS.
------------------------------------------------------------------------


    Note 5: Groups 4 and 5 airplanes had the butterfly plates 
installed at the factory.

    (f) If any cracks are found in any inspection required by this 
AD, you must repair the cracks or replace the lower wing spar before 
further flight.
    (1) Use the cold work process to ream out small cracks as 
defined in Ayres Corporation Service Bulletin No. SB-AG-39, dated 
September 17, 1996; or
    (2) Ream the \1/4\-inch bolt holes to \5/16\ inches diameter as 
defined in Part I of Ayres Corporation Custom Kit No. CK-AG-29, 
dated December 23, 1997; or
    (3) Install Kaplan Splice Blocks as defined in Quality 
Aerospace, Inc. Custom Kit No. CK-AG-30, dated December 6, 2001; or
    (4) Replace the affected spar cap in accordance with the 
maintenance manual.

    Note 6: 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 Corporation Custom 
Kit No. CK-AG-29, Part I, dated December 23, 1997, also provides 
procedures to ream the \1/4\-inch bolt hole to \5/16\ inches 
diameter, which may remove a small crack. Resizing the holes to the 
required size to install a Kaplan splice block may also remove small 
cracks. If you use any of these methods to remove cracks and the 
airplane is re-inspected immediately with no cracks found, you may 
continue to follow the repetitive inspection intervals for your 
airplane listed in paragraphs (e)(5), (e)(6), or (e)(7) of this AD.


    (g) For all inspection methods (magnetic particle, ultrasonic, 
or eddy current), hours TIS for initial and repetitive inspections 
intervals start over when wing spar is replaced.
    (1) If the wings or wing spars were replaced with new or used 
wings or wing spars during the life of the airplane and logbook 
records positively show the hours TIS of the wings or wing spars, 
then initially inspect at applicable wing or wing spar times in 
paragraph (e)(3) and repetitively inspect at intervals in paragraphs 
(e)(5), (e)(6), or (e)(7) of this AD.
    (2) If the wings or wing spars were replaced with new or used 
wings or wing spars during the life of the airplane and logbook 
records cannot positively show the hours TIS of the wings or wing 
spars, then inspect within 25 hours TIS after April 18, 2006 (the 
effective date of this AD), unless already done, and repetitively 
inspect at intervals in paragraphs (e)(5), (e)(6), or (e)(7) of this 
AD.
    (h) Report any cracks you find within 10 days after the cracks 
are found or within 10 days after April 18, 2006 (the effective date 
of this AD), whichever occurs later. Send your report to Cindy 
Lorenzen, Aerospace Engineer, ACE-115A, Atlanta ACO, One Crown 
Center, 1895 Phoenix Blvd., Suite 450, Atlanta, GA 30349; telephone: 
(770) 703-6078; facsimile: (770) 703-6097; e-mail: 
[email protected]. The Office of Management and Budget (OMB) 
approved the information collection requirements contained in this 
regulation under the provisions of the Paperwork Reduction Act and 
assigned OMB Control Number 2120-0056. Include in your report the 
following information:
    (1) Aircraft model and serial number;
    (2) Engine model;
    (3) Aircraft hours TIS;
    (4) Left and right wing lower spar cap hours TIS;
    (5) Hours TIS on the spar cap since last inspection;
    (6) Crack location and size;
    (7) Procedure (magnetic particle, ultrasonic, or eddy current) 
used for the last inspection; and
    (8) Information on corrective action taken, whether cold working 
has been done or modifications incorporated such as installation of 
butterfly plates, and when this corrective action was taken.

[[Page 16696]]

Alternative Methods of Compliance (AMOCs)

    (i) The Manager, Atlanta Aircraft Certification Office, FAA, 
ATTN: Cindy Lorenzen, Aerospace Engineer, ACE-115A, Atlanta Aircraft 
Certification Office, One Crown Center, 1895 Phoenix Blvd., Suite 
450, Atlanta, GA 30349; telephone: (770) 703-6078; facsimile: (770) 
703-6097; e-mail: [email protected]; or Mike Cann, Aerospace 
Engineer, ACE-117A, Atlanta Aircraft Certification Office, One Crown 
Center, 1895 Phoenix Blvd., Suite 450, Atlanta, Georgia 30349; 
telephone: (770) 703-6038; facsimile: (770) 703-6097; e-mail: 
[email protected], has the authority to approve AMOCs for this 
AD, if requested using the procedures in 14 CFR 39.
    (j) AMOCs approved for AD 2003-07-01, AD 2000-11-16, AD 97-13-
11, and/or AD 97-17-03 are approved as AMOCs for this AD.

Material Incorporated by Reference

    (k) You must do the actions required by this AD following the 
instructions in Ayres Corporation Service Bulletin No. SB-AG-39, 
dated September 17, 1996; Ayres Corporation Custom Kit No. CK-AG-29, 
dated December 23, 1997; and Quality Aerospace, Inc. Custom Kit No. 
CK-AG-30, dated December 6, 2001.
    (1) As of July 25, 2000 (65 FR 36055), the Director of the 
Federal Register previously approved the incorporation by reference 
of Ayres Corporation Service Bulletin No. SB-AG-39, dated September 
17, 1996; and Ayres Corporation Custom Kit No. CK-AG-29, dated 
December 23, 1997, in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51.
    (2) As of May 20, 2003 (68 FR 15653), the Director of the 
Federal Register previously approved the incorporation by reference 
of Quality Aerospace, Inc. Custom Kit No. CK-AG-30, dated December 
6, 2001, in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
    (3) To get a copy of this service information, contact Thrush 
Aircraft, Inc. at 300 Old Pretoria Road, P.O. Box 3149, Albany, 
Georgia 31706-3149 or go to http://www.thrushaircraft.com. To review 
copies of this service information, go to the National Archives and 
Records Administration (NARA). For information on the availability 
of this material at NARA, go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html or call 
(202) 741-6030. To view the AD docket, go to the Docket Management 
Facility; U.S. Department of Transportation, 400 Seventh Street, 
SW., Nassif Building, Room PL-401, Washington, DC 20590-001 or on 
the Internet at http://dms.dot.gov. The docket number is FAA-2006-
23649; Directorate Identifier 2006-CE-08-AD.

    Issued in Kansas City, Missouri, on March 28, 2006.
David R. Showers,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 06-3162 Filed 4-3-06; 8:45 am]
BILLING CODE 4910-13-P