[Federal Register Volume 63, Number 251 (Thursday, December 31, 1998)]
[Rules and Regulations]
[Pages 72132-72137]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-34384]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-CE-72-AD; Amendment 39-10972; AD 99-01-05]
RIN 2120-AA64


Airworthiness Directives; All Airplane Models of The New Piper 
Aircraft, Inc. (formerly Piper Aircraft Corporation) That Are Equipped 
with Wing Lift Struts

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes Airworthiness Directive (AD) 93-10-
06, which currently requires repetitively inspecting the wing lift 
struts and wing lift strut forks for cracks or corrosion on all 
airplane models of The New Piper Aircraft, Inc. (Piper) that are 
equipped with wing lift struts, and replacing any strut or fork found 
cracked or corroded. This AD clarifies certain requirements of AD 93-
10-06, eliminates the lift strut fork repetitive inspection requirement 
on the Piper PA-25 series airplanes, incorporates models inadvertently 
omitted from AD 93-10-06, and requires fabricating and installing a 
placard on the lift strut. This AD results from reports, questions, and 
information received from the field on AD 93-10-06, which show a need 
to clarify and add information that will more fully achieve the safety 
intent of that AD. The actions specified by this AD are intended to 
prevent in-flight separation of the wing from the airplane caused by 
corroded wing lift struts or cracked wing lift forks, which could 
result in loss of control of the airplane.

DATES: Effective February 8, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of February 8, 1999.

ADDRESSES: The service bulletins referenced in this AD may be obtained 
from The New Piper Aircraft, Inc., Customer Services, 2926 Piper Drive, 
Vero Beach, Florida 32960. Copies of the instructions to the Jensen 
Aircraft STC's may be obtained from Jensen Aircraft, Inc., 9225 County 
Road 140, Salida, Colorado 81201. Copies of the instructions to the F. 
Atlee Dodge STC may be obtained from F. Atlee Dodge, Aircraft Services, 
Inc., P.O. Box 190409, Anchorage, Alaska 99519-0409. This information 
may also be examined at the Federal Aviation Administration

[[Page 72133]]

(FAA), Central Region, Office of the Regional Counsel, Attention: Rules 
Docket No. 96-CE-72-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: William O. Herderich, Aerospace 
Engineer, FAA, Atlanta Certification Office, One Crown Center, 1895 
Phoenix Boulevard, suite 450, Atlanta, Georgia 30349; telephone: (770) 
703-6084; facsimile: (770) 703-6097.

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 all Piper airplane 
models equipped with wing lift struts was published in the Federal 
Register as a notice of proposed rulemaking (NPRM) on April 23, 1998, 
(63 FR 20143). The NPRM proposed to supersede AD 93-10-06, Amendment 
39-8586 (58 FR 29965, May 25, 1993), which currently requires 
repetitively inspecting the wing lift struts and wing lift strut forks 
for cracks or corrosion, and replacing any strut or fork found cracked 
or corroded. The NPRM proposed to retain the requirements of 
repetitively inspecting the wing lift struts and wing lift strut forks 
for cracks or corrosion, and replacing any strut or fork found cracked 
or corroded. The proposed NPRM would also clarify certain requirements 
of AD 93-10-06, eliminate the lift strut fork repetitive inspection 
requirement on the Piper PA-25 series airplanes, incorporate airplane 
models inadvertently omitted from the applicability of AD 93-10-06, and 
require installing a placard on the lift strut. Accomplishment of the 
inspections specified in the NPRM would be required in accordance with 
Piper Service Bulletin (SB) No. 528D, dated October 19, 1990, or Piper 
SB No. 910A, dated October 10, 1989; or the Appendix to the proposed 
AD.
    Accomplishment of the installation as specified in the NPRM would 
be required in accordance with one of the following:

--The maintenance manual for original equipment manufacturer (OEM) wing 
lift struts or new sealed wing lift strut assemblies as referenced in 
Piper SB 528D, dated October 19, 1990, or Piper SB No. 910A, dated 
October 10, 1989;
--F. Atlee Dodge Instructions No. 3233-I for Modified Piper Wing Lift 
Struts (STC SA4635NM), dated February 1, 1991; or
--Jensen Aircraft Installation Instructions for Modified Lift Strut 
Fittings, which incorporates the following pages:

------------------------------------------------------------------------
            Pages                Revision level             Date
------------------------------------------------------------------------
1 and 5.....................  Original Issue......  July 15, 1983.
2, 4, and 6.................  Revision No. 1......  March 30, 1984.
a and 3.....................  Revision No. 2......  April 20, 1984.
------------------------------------------------------------------------

    The NPRM was the result of reports, questions, and information 
received from the field on AD 93-10-06, which show a need to clarify 
and add information that will more fully achieve the safety intent of 
that AD.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the two comments received.

Comment Disposition

    Both commenters request that the FAA reference Univair Aircraft 
Corporation lift strut assemblies in the AD. Univair holds a parts 
manufacturer approval (PMA) for parts that are identical to the 
improved design Piper lift strut assemblies referenced in the NPRM.
    The FAA does not concur. FAA policy is to not reference PMA parts 
in AD's, unless the FAA determines that the unsafe condition applies to 
the PMA parts. If these Univair parts are installed, then the actions 
of this AD would not apply because the parts are an FAA-approved 
equivalent to the improved design Piper lift strut assemblies that, 
when installed, eliminate the repetitive inspection requirement of the 
AD.
    No changes have been made to the AD based on 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 
minor editorial corrections. The FAA has determined that these minor 
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 22,000 airplanes in the U.S. registry will 
be affected by this AD, that it will take approximately 8 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 this AD on U.S. operators is estimated to be 
$10,560,000, or $480 per airplane.
    These figures are based only on the cost of the initial inspection 
and do not account for the costs of any repetitive inspections. The FAA 
has no way of determining how many repetitive inspections each owner/
operator will incur over the life of the airplane. The FAA also has no 
way of determining how many airplanes have improved design wing lift 
struts and forks installed. This will eliminate the requirements of 
this AD, and thus reduce the cost impact of this AD upon the public.
    AD 93-10-06 currently requires the same actions as proposed in this 
document. The only differences between AD 93-10-06 and this AD are the 
addition of ultrasonic methods as an option for accomplishing the 
inspections, the elimination of the requirement of inspecting the lift 
strut forks on Piper PA-25 series airplanes, the addition of certain 
airplane models equipped with Piper lift strut assemblies, the addition 
of the requirement of installing the ``NO STEP'' placard on the wing 
lift struts, and editorial corrections and additions for clarification 
purposes.

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.

[[Page 72134]]

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 removing Airworthiness Directive 
(AD) 93-10-06, Amendment 39-8536 (58 FR 29965, May 25, 1993), and by 
adding a new AD to read as follows:

99-01-05  The New Piper Aircraft, Inc.: Amendment 39-10972; Docket 
No. 96-CE-72-AD; Supersedes AD 93-10-06, Amendment 39-8536.

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

------------------------------------------------------------------------
                    Models                           Serial numbers
------------------------------------------------------------------------
TG-8 (Army TG-8, Navy XLNP-1)................  All serial numbers.
E-2 and F-2..................................  All serial numbers.
J3C-40, J3C-50, J3C-50S, (Army L-4, L-4B, L-   All serial numbers.
 4H, and L-4J), J3C-65 (Navy NE-1 and NE-2),
 J3C-65S J3F-50, J3F-50S, J3F-60, J3F-60S,
 J3F-65 (Army L-4D), J3F-65S, J3L, J3L-S, J3L-
 65 (Army L-4C), and J3L-65S.
J4, J4A, J4A-S, and J4E (Army L-4E)..........  4-401 through 4-1649.
J5A (Army L-4F), J5A-80, J5B (Army L-4G),      All serial numbers.
 J5C, L-14, AE-1, and HE-1.
PA-11 and PA-11S.............................  11-1 through 11-1678.
PA-12 and PA-12S.............................  12-1 through 12-4036.
PA-14........................................  14-1 through 14-523.
PA-15........................................  15-1 through 15-388.
PA-16 and PA-16S.............................  16-1 through 16-736.
PA-17........................................  17-1 through 17-215.
PA-18, PA-18S, PA-18 ``105'' (Special), PA-    18-1 through 18-8309025,
 18S ``105'' (Special), PA-18A, PA-18 ``125''   189001 through 1809032,
 (Army L-21A), PA-18S ``125'', PA-18AS          and 1809034 through
 ``125'', PA-18 ``135'' (Army L-21B), PA-18A    1809040.
 ``135'', PA-18S ``135'', PA-18AS ``135'', PA-
 18 ``150'', PA-18A ``150'', PA-18S ``150'',
 PA-18AS ``150'', PA-18A (Restricted), PA-18A
 ``135'' (Restricted), and PA-18A ``150''
 (Restricted).
PA-19 (Army L-18C), and PA-19S...............  19-1, 19-2, and 19-3.
PA-20, PA-20S, PA-20 ``115'', PA-20S ``115'',  20-1 through 20-1121.
 PA-20 ``135'', and PA-20S ``135''.
PA-22, PA-22-108, PA-22-135, PA-22S-135, PA-   22-1 through 22-9848.
 22-150, PA-22S-150, PA-22-160, and PA-22S-
 160.
PA-25, PA-25-235, and PA-25-260..............  25-1 through 25-8156024.
------------------------------------------------------------------------

    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 (f) 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 prevent in-flight separation of the wing from the airplane 
caused by corroded wing lift struts or cracked wing lift strut 
forks, which could result in loss of control of the airplane, 
accomplish the following:

    Note 2: 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 4: (A), (B), (C), etc.

Level 2, Level 3, and Level 4 structures are designations of the 
Level 1 paragraph they immediately follow.
    (a) For all affected airplane models, within 1 calendar month 
after the effective date of this AD or within 24 calendar months 
after the last inspection accomplished in accordance with AD 93-10-
06 (superseded by this action), whichever occurs later, remove the 
wing lift struts in accordance with Piper Service Bulletin (SB) No. 
528D, dated October 19, 1990, or Piper SB No. 910A, dated October 
10, 1989, as applicable, and accomplish one of the following (the 
actions in either paragraph (a)(1), (a)(2), (a)(3), (a)(4), or 
(a)(5); including subparagraphs, of this AD):
    (1) Inspect the wing lift struts for corrosion in accordance 
with the ``Instructions'' section in Part I of either Piper SB No. 
528D, dated October 19, 1990, or Piper SB No. 910A, dated October 
10, 1989, as applicable.
    (i) If no perceptible dents (as defined in the above SB's) are 
found in the wing lift strut and no corrosion is externally visible, 
prior to further flight, apply corrosion inhibitor to each strut in 
accordance with whichever of the above SB's that is applicable. 
Reinspect the lift struts at intervals not to exceed 24 calendar 
months and accomplish any of the requirements of paragraph (a) of 
this AD, including all subparagraphs.
    (ii) If a perceptible dent (as defined in the above SB's) is 
found in the wing lift strut or external corrosion is found, prior 
to further flight, accomplish one of the installations (and 
subsequent actions presented in each paragraph) specified in 
paragraphs (a)(3), (a)(4), or (a)(5) of this AD.
    (2) Inspect the wing lift struts for corrosion in accordance 
with the Appendix to this AD. The inspection procedures in this 
Appendix must be accomplished by a Level 2 inspector certified using 
the guidelines established by the American Society for Non-
destructive Testing, or MIL-STD-410.
    (i) If no corrosion is found that is externally visible and all 
requirements in the Appendix to this AD are met, prior to further 
flight, apply corrosion inhibitor to each strut in accordance with 
whichever of the above SB's that is applicable. Reinspect the lift 
struts at intervals not to exceed 24 calendar months and accomplish 
any of the requirements of paragraph (a) of this AD, including all 
subparagraphs.
    (ii) If external corrosion is found or if any of the 
requirements in the Appendix of this AD are not met, prior to 
further flight, accomplish one of the installations (and subsequent 
actions presented in each paragraph) specified in paragraphs (a)(3), 
(a)(4), or (a)(5) of this AD.
    (3) Install original equipment manufacturer (OEM) part number 
wing struts (or FAA-approved equivalent part numbers) that have been 
inspected in accordance with the specifications presented in either 
paragraph (a)(1) or (a)(2) of this AD, and are found to be airworthy 
according to the inspection requirements included in these 
paragraphs. Thereafter, inspect these wing lift struts at intervals 
not to exceed 24 calendar months in accordance with the 
specifications presented in either paragraph (a)(1) or (a)(2) of 
this AD.
    (4) Install new sealed wing lift strut assemblies, part numbers 
as specified in Piper SB No. 528D and Piper SB No. 910A (or FAA-
approved equivalent part numbers) on each wing as specified in the 
Instructions section in Part II of the above-referenced

[[Page 72135]]

SB's. These sealed wing lift strut assemblies also include the wing 
lift strut forks. Installation of these assemblies constitute 
terminating action for the inspection requirements of both 
paragraphs (a) and (b) of this AD.
    (5) Install F. Atlee Dodge wing lift strut assemblies in 
accordance with F. Atlee Dodge Installation Instructions No. 3233-I 
for Modified Piper Wing Lift Struts (Supplemental Type Certificate 
(STC) SA4635NM), dated February 1, 1991. Thereafter, inspect these 
wing lift struts at intervals not to exceed 60 calendar months in 
accordance with the specifications presented in paragraph (a)(1) or 
(a)(2) of this AD.
    (b) For all affected airplane models, except for Models PA-25, 
PA-25-235, and PA-25-260, within the next 100 hours time-in-service 
(TIS) after the effective date of this AD or within 500 hours TIS 
after the last inspection accomplished in accordance with AD 93-10-
06 (superseded by this action), whichever occurs later, remove the 
wing lift strut forks, and accomplish one of the following (the 
actions in either paragraph (b)(1), (b)(2), (b)(3), (b)(4), or 
(b)(5); including subparagraphs, of this AD):
    (1) Inspect the wing lift strut forks using FAA-approved 
magnetic particle procedures.
    (i) If no cracks are found, reinspect at intervals not to exceed 
500 hours TIS provided that the replacement requirements of 
paragraphs (b)(1)(ii)(B) and (b)(1)(ii)(C) of this AD have been met.
    (ii) Replace the wing lift strut forks at whichever of the 
following is applicable:
    (A) If cracks are found on any wing lift strut fork: Prior to 
further flight;
    (B) If the airplane is equipped with floats or has been equipped 
with floats within the last 2,000 hours TIS and no cracks are found 
during the above inspections: Upon accumulating 1,000 hours TIS on 
the wing lift strut forks or within the next 100 hours TIS, 
whichever occurs later; or
    (C) If the airplane has not been equipped with floats within the 
last 2,000 hours TIS and no cracks are found during the above 
inspections: Upon accumulating 2,000 hours TIS on the wing lift 
strut forks or within the next 100 hours TIS, whichever occurs 
later.
    (iii) Replacement parts shall be of the same part numbers of the 
existing part (or FAA-approved equivalent part numbers) and shall be 
manufactured with rolled threads. Lift strut forks manufactured with 
machined (cut) threads shall not be utilized.
    (iv) The 500-hour TIS interval repetitive inspections are still 
required when the above replacements are accomplished.
    (2) Install new OEM part number wing lift strut forks (or FAA-
approved equivalent part numbers). Reinspect and replace these wing 
lift strut forks at the intervals specified in paragraphs (b)(1)(i), 
(b)(1)(ii), (b)(1)(iii), and (b)(1)(iv), including all 
subparagraphs, of this AD.
    (3) Install new sealed wing lift strut assemblies, part numbers 
as specified in Piper SB No. 528D and Piper SB No. 910A (or FAA-
approved equivalent part numbers) on each wing, as specified in the 
Instructions section in Part II of the above-referenced SB's.
    (i) This installation may have ``already been accomplished'' 
through the actions specified in paragraph (a)(4) of this AD.
    (ii) No repetitive inspections are required after installing 
these sealed wing lift strut assemblies.
    (4) Install Jensen Aircraft wing lift strut fork assemblies as 
specified in the STC's presented in the paragraphs that follow, as 
applicable, in accordance with Jensen Aircraft Installation 
Instructions for Modified Lift Strut Fittings, which incorporates 
the following pages:

------------------------------------------------------------------------
            Pages                Revision level             Date
------------------------------------------------------------------------
1 and 5.....................  Original Issue......  July 15, 1983.
2, 4, and 6.................  Revision No. 1......  March 30, 1984.
a and 3.....................  Revision No. 2......  April 20, 1984.
------------------------------------------------------------------------

No repetitive inspections are required after installing these Jensen 
Aircraft wing lift strut fork assemblies; however, repetitive 
inspections of the lift strut are required as specified in paragraph 
(a)(1), (a)(2), or (a)(3) of this AD:
    (i) For Models PA-12 and PA-12S airplanes: STC SA1583NM;
    (ii) For Model PA-14 airplanes: STC SA1584NM;
    (iii) For the Models PA-16 and PA-16S airplanes: STC SA1590NM;
    (iv) For the Models PA-18, PA-18S, 189001 PA-18 ``105'' 
(Special), PA-18S ``105'' (Special), PA-18A, PA-18 ``125'' (Army L-
21A), PA-18S ``125'', PA-18AS ``125'', PA-18 ``135'' (Army L-21B), 
PA-18A ``135'', PA-18S ``135'', PA-18S ``135'', PA-18AS ``135'', PA-
18 ``150'', PA-18A ``150'', PA-18S ``150'', PA-18AS ``150'', PA-18A 
(Restricted), PA-18A ``135'' (Restricted), and PA-18A ``150'' 
(Restricted) airplanes: STC SA1585NM;
    (v) For the Models PA-20, PA-20S, PA-20 ``115'', PA-20S ``115'', 
PA-20 ``135'', and PA-20S ``135'' airplanes: STC SA1586NM; and
    (vi) For the Model PA-22 airplanes: STC SA1587NM.
    (5) Install F. Atlee Dodge wing lift strut assemblies in 
accordance with F. Atlee Dodge Installation Instructions No. 3233-I 
for Modified Piper Wing Lift Struts (STC SA4635NM), dated February 
1, 1991.
    (i) No repetitive inspections of the wing lift strut forks are 
required when these assemblies are installed.
    (ii) This installation may have ``already been accomplished'' 
through the actions specified in paragraph (a)(5) of this AD.
    (c) If holes are drilled, in either one of the scenarios 
presented in paragraphs (c)(1) and (c)(2) of this AD, to attach 
cuffs, door clips, or other hardware, inspect the wing lift struts 
at intervals not to exceed 24 calendar months using the procedures 
specified in paragraphs (a)(1) and (a)(2), including all 
subparagraphs, of this AD:
    (1) Wing lift strut assemblies installed in accordance with 
(a)(4) or (b)(3) of this AD; or
    (2) F. Atlee Dodge wing lift strut assemblies installed in 
accordance with paragraph (a)(5) or (b)(5) of this AD.
    (d) For all affected airplane models, within 1 calendar month 
after the effective date of this AD or within 24 calendar months 
after the last inspection accomplished in accordance with AD 93-10-
06 (superseded by this action), whichever occurs later, and 
thereafter prior to further flight after the installation of any 
lift strut assembly, accomplish one of the following:
    (1) Install ``NO STEP'' decal, Piper part number (P/N) 80944-02, 
on each wing lift strut approximately 6 inches from the bottom of 
the struts in a way that the letters can be read when entering and 
exiting the aircraft; or
    (2) Paint the statement ``NO STEP'' approximately 6 inches from 
the bottom of the struts in a way that the letters can be read when 
entering and exiting the aircraft. Use a minimum of 1-inch letters 
using a color that contrasts with the color of the airplane.
    (e) Special flight permits may be issued in accordance with 
sections 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.
    (f) 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, Atlanta Aircraft 
Certification Office (ACO), One Crown Center, 1895 Phoenix 
Boulevard, suite 450, Atlanta, Georgia 30349.
    (1) The request shall be forwarded through an appropriate FAA 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Atlanta ACO.
    (2) Alternative methods of compliance approved in accordance 
with AD 93-10-06, Amendment 39-8536, are considered approved as 
alternative methods of compliance for this AD.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Atlanta Aircraft Certification Office.

    (g) The inspections required by this AD shall be done in 
accordance with Piper Service Bulletin No. 528D, dated October 19, 
1990, and Piper Service Bulletin No. 910A, dated October 10, 1989. 
The installation required by this AD shall be done in accordance 
with F. Atlee Dodge Installation Instructions No. 3233-I for 
Modified Piper Wing Lift Struts (Supplemental Type Certificate (STC) 
SA4635NM), dated February 1, 1991, and Jensen Aircraft Installation 
Instructions for Modified Lift Strut Fittings, which incorporates 
the following pages:

------------------------------------------------------------------------
            Pages                Revision level             Date
------------------------------------------------------------------------
1 and 5.....................  Original Issue......  July 15, 1983.
2, 4, and 6.................  Revision No. 1......  March 30, 1984.
a and 3.....................  Revision No. 2......  April 20, 1984.
------------------------------------------------------------------------

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. The service bulletins referenced in this AD may be obtained from 
The New Piper Aircraft, Inc., Customer Services, 2926 Piper Drive, 
Vero Beach, Florida 32960. Copies of the instructions to

[[Page 72136]]

the Jensen Aircraft STC's may be obtained from Jensen Aircraft, 9225 
County Road 140, Salida, Colorado 81201. Copies of the instructions 
to the F. Atlee Dodge STC may be obtained from F. Atlee Dodge, 
Aircraft Services, Inc., P.O. Box 190409, Anchorage, Alaska 99519-
0409. 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.
    (h) This amendment supersedes AD 93-10-06, Amendment 39-8536.
    (i) This amendment becomes effective on February 8, 1999.

Appendix to AD 99-01-05; Amendment 39-10972; Docket No. 96-CE-72-AD

Procedures and Requirements for Ultrasonic Inspection of Piper Wing 
Lift Struts

Equipment Requirements

    1. A portable ultrasonic thickness gauge or flaw detector with 
echo-to-echo digital thickness readout capable of reading to 0.001-
inch and an A-trace waveform display will be needed to accomplish 
this inspection.
    2. An ultrasonic probe with the following specifications will be 
needed to accomplish this inspection: 10 MHz (or higher), 0.283-inch 
(or smaller) diameter dual element or delay line transducer designed 
for thickness gauging. The transducer and ultrasonic system shall be 
capable of accurately measuring the thickness of AISI 4340 steel 
down to 0.020-inch. An accuracy of +/-0.002-inch throughout a 0.020-
inch to 0.050-inch thickness range while calibrating shall be the 
criteria for acceptance.
    3. Either a precision machined step wedge made of 4340 steel (or 
similar steel with equivalent sound velocity) or at least three shim 
samples of same material will be needed to accomplish this 
inspection. One thickness of the step wedge or shim shall be less 
than or equal to 0.020-inch, one shall be greater than or equal to 
0.050-inch, and at least one other step or shim shall be between 
these two values.
    4. Glycerin, light oil, or similar non-water based ultrasonic 
couplants are recommended in the setup and inspection procedures. 
Water-based couplants, containing appropriate corrosion inhibitors, 
may be utilized, provided they are removed from both the reference 
standards and the test item after the inspection procedure is 
completed and adequate corrosion prevention steps are then taken to 
protect these items.

     Note: Couplant is defined as ``a substance used between 
the face of the transducer and test surface to improve transmission 
of ultrasonic energy across the transducer/strut interface.''
     Note: If surface roughness due to paint loss or 
corrosion is present, the surface should be sanded or polished 
smooth before testing to assure a consistent and smooth surface for 
making contact with the transducer. Care shall be taken to remove a 
minimal amount of structural material. Paint repairs may be 
necessary after the inspection to prevent further corrosion damage 
from occurring. Removal of surface irregularities will enhance the 
accuracy of the inspection technique.

Instrument Setup

    1. Set up the ultrasonic equipment for thickness measurements as 
specified in the instrument's user's manual. Because of the variety 
of equipment available to perform ultrasonic thickness measurements, 
some modification to this general setup procedure may be necessary. 
However, the tolerance requirement of step 13 and the record keeping 
requirement of step 14, must be satisfied.
    2. If battery power will be employed, check to see that the 
battery has been properly charged. The testing will take 
approximately two hours. Screen brightness and contrast should be 
set to match environmental conditions.
    3. Verify that the instrument is set for the type of transducer 
being used, i.e. single or dual element, and that the frequency 
setting is compatible with the transducer.
    4. If a removable delay line is used, remove it and place a drop 
of couplant between the transducer face and the delay line to assure 
good transmission of ultrasonic energy. Reassemble the delay line 
transducer and continue.
    5. Program a velocity of 0.231-inch/microsecond into the 
ultrasonic unit unless an alternative instrument calibration 
procedure is used to set the sound velocity.
    6. Obtain a step wedge or steel shims per item 3 of the 
Equipment Requirements. Place the probe on the thickest sample using 
couplant. Rotate the transducer slightly back and forth to ``ring'' 
the transducer to the sample. Adjust the delay and range settings to 
arrive at an A-trace signal display with the first backwall echo 
from the steel near the left side of the screen and the second 
backwall echo near the right of the screen. Note that when a single 
element transducer is used, the initial pulse and the delay line/
steel interface will be off of the screen to the left. Adjust the 
gain to place the amplitude of the first backwall signal at 
approximately 80% screen height on the A-trace.
    7. ``Ring'' the transducer on the thinnest step or shim using 
couplant. Select positive half-wave rectified, negative half-wave 
rectified, or filtered signal display to obtain the cleanest signal. 
Adjust the pulse voltage, pulse width, and damping to obtain the 
best signal resolution. These settings can vary from one transducer 
to another and are also user dependent.
    8. Enable the thickness gate, and adjust the gate so that it 
starts at the first backwall echo and ends at the second backwall 
echo. (Measuring between the first and second backwall echoes will 
produce a measurement of the steel thickness that is not affected by 
the paint layer on the strut). If instability of the gate trigger 
occurs, adjust the gain, gate level, and/or damping to stabilize the 
thickness reading.
    9. Check the digital display reading and if it does not agree 
with the known thickness of the thinnest thickness, follow your 
instrument's calibration recommendations to produce the correct 
thickness reading. When a single element transducer is used this 
will usually involve adjusting the fine delay setting.
    10. Place the transducer on the thickest step of shim using 
couplant. Adjust the thickness gate width so that the gate is 
triggered by the second backwall reflection of the thick section. If 
the digital display does not agree with the thickest thickness, 
follow your instruments calibration recommendations to produce the 
correct thickness reading. A slight adjustment in the velocity may 
be necessary to get both the thinnest and the thickest reading 
correct. Document the changed velocity value.
    11. Place couplant on an area of the lift strut which is thought 
to be free of corrosion and ``ring'' the transducer to surface. 
Minor adjustments to the signal and gate settings may be required to 
account for coupling improvements resulting from the paint layer. 
The thickness gate level should be set just high enough so as not to 
be triggered by irrelevant signal noise. An area on the upper 
surface of the lift strut above the inspection area would be a good 
location to complete this step and should produce a thickness 
reading between 0.034-inch and 0.041-inch.
    12. Repeat steps 8, 9, 10, and 11 until both thick and thin shim 
measurements are within tolerance and the lift strut measurement is 
reasonable and steady.
    13. Verify that the thickness value shown in the digital display 
is within +/-0.002-inch of the correct value for each of the three 
or more steps of the setup wedge or shims. Make no further 
adjustments to the instrument settings.
    14. Record the ultrasonic versus actual thickness of all wedge 
steps or steel shims available as a record of setup.

Inspection Procedure

    1. Clean the lower 18 inches of the wing lift struts using a 
cleaner that will remove all dirt and grease. Dirt and grease will 
adversely affect the accuracy of the inspection technique. Light 
sanding or polishing may also be required to reduce surface 
roughness as noted in the Equipment Requirements section.
    2. Using a flexible ruler, draw a \1/4\-inch grid on the surface 
of the first 11 inches from the lower end of the strut as shown in 
Piper Service Bulletin No. 528D or 910A, as applicable. This can be 
done using a soft (#2) pencil and should be done on both faces of 
the strut. As an alternative to drawing a complete grid, make two 
rows of marks spaced every \1/4\-inch across the width of the strut. 
One row of marks should be about 11 inches from the lower end of the 
strut, and the second row should be several inches away where the 
strut starts to narrow. Lay the flexible ruler between respective 
tick marks of the two rows and use tape or a rubber band to keep the 
ruler in place. See Figure 1.
    3. Apply a generous amount of couplant inside each of the square 
areas or along the edge of the ruler. Re-application of couplant may 
be necessary.
    4. Place the transducer inside the first square area of the 
drawn grid or at the first \1/4\-inch mark on the ruler and ``ring'' 
the transducer to the strut. When using a dual element transducer, 
be very careful to record the thickness value with the axis of the 
transducer elements perpendicular to any curvature in the strut. If 
this is not done, loss of signal or inaccurate readings can result.
    5. Take readings inside each square on the grid or at \1/4\-inch 
increments along the ruler

[[Page 72137]]

and record the results. When taking a thickness reading, rotate the 
transducer slightly back and forth and experiment with the angle of 
contact to produce the lowest thickness reading possible. Pay close 
attention to the A-scan display to assure that the thickness gate is 
triggering off of maximized backwall echoes.

     Note: A reading shall not exceed .041-inch. If a 
reading exceeds .041-inch, repeat steps 13 and 14 of the Instrument 
Setup section before proceeding further.

    6. If the A-trace is unsteady or the thickness reading is 
clearly wrong, adjust the signal gain and/or gate setting to obtain 
reasonable and steady readings. If any instrument setting is 
adjusted, repeat steps 13 and 14 of the Instrument Setup section 
before proceeding further.
    7. In areas where obstructions are present, take a data point as 
close to the correct area as possible.

     Note: The strut wall contains a fabrication bead at 
approximately 40% of the strut chord. The bead may interfere with 
accurate measurements in that specific location.

    8. A measurement of 0.024-inch or less shall require replacement 
of the strut prior to further flight.
    9. If at any time during testing an area is encountered where a 
valid thickness measurement cannot be obtained due to a loss of 
signal strength or quality, the area shall be considered suspect. 
These areas may have a remaining wall thickness of less than 0.020-
inch, which is below the range of this setup, or they may have small 
areas of localized corrosion or pitting present. The latter case 
will result in a reduction in signal strength due to the sound being 
scattered from the rough surface and may result in a signal that 
includes echoes from the pits as well as the backwall. The suspect 
area(s) shall be tested with a Maule ``Fabric Tester'' as specified 
in Piper Service Bulletin No. 528D or 910A.
    10. Record the lift strut inspection in the aircraft log book.

BILLING CODE 4910-13-P
[GRAPHIC] [TIFF OMITTED] TR31DE98.002


    Issued in Kansas City, Missouri, on December 22, 1998.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 98-34384 Filed 12-30-98; 8:45 am]
BILLING CODE 4910-13-C