[Federal Register Volume 63, Number 139 (Tuesday, July 21, 1998)]
[Rules and Regulations]
[Pages 39018-39022]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-19328]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-CE-01-AD; Amendment 39-10669; AD 98-15-18]
RIN 2120-AA64


Airworthiness Directives; Maule Aerospace Technology Corp. M-4, 
M-5, M-6, M-7, MX-7, and MXT-7 Series Airplanes and Models MT-7-235 and 
M-8-235 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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

SUMMARY: This amendment supersedes Airworthiness Directive (AD) 95-26-
18, which currently requires inspecting (one-time) certain wing lift 
struts for internal corrosion on certain Maule Aerospace Technology 
Corp. (Maule) M-4, M-5, M-6, M-7, MX-7, and MXT-7 series airplanes and 
Models MT-7-235 and M-8-235 airplanes, and replacing any wing lift 
strut where corrosion is found. That AD was the result of an accident 
where the wing separated from one of the affected airplanes. This AD 
retains the initial inspection and possible replacement requirements of 
AD 95-26-18, requires the inspections to be repetitive, and provides 
the option of using ultrasonic procedures to accomplish the inspection 
requirements. The actions specified by this AD are intended to prevent 
failure of the wing lift struts caused by corrosion damage, which could 
eventually result in the wing separating from the airplane.

DATES: Effective September 9, 1998.
    The incorporation by reference of Maule Service Bulletin No. 11, 
dated October 30, 1995, as listed in the regulations was previously 
approved by the Director of the Federal Register as of January 26, 1996 
(61 FR 623, January 9, 1996).

ADDRESSES: Service information that applies to this AD may be obtained 
from Maule Aerospace Technology Inc., 2099 GA. Hwy. 133 South, 
Moultrie, Georgia 31768; telephone: (912) 985-2045; facsimile: (912) 
890-2402. This information may also be examined at the Federal Aviation 
Administration (FAA), Central Region, Office of the Regional Counsel, 
Attention: Rules Docket No. 98-CE-01-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: Cindy Lorenzen, Aerospace Engineer, 
FAA, Atlanta Aircraft Certification Office, One Crown Center, 1895 
Phoenix Boulevard, suite 450, Atlanta, Georgia 30349; telephone: (770) 
703-6078; 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 supersede AD 95-26-18, Amendment 39-9476 (61 FR 623, 
January 9, 1996), that applies to certain Maule M-4, M-5, M-6, M-7, MX-
7, and MXT-7 series airplanes and Models MT-7-235 and M-8-235 airplanes 
that are equipped with part number (P/N) 2079E rear wing lift struts 
and P/N 2080E front wing lift struts, was published in the Federal 
Register as a notice of proposed rulemaking (NPRM) on March 24, 1998 
(63 FR 14051). AD 95-26-18 currently requires inspecting (one-time) the 
wing lift struts for internal corrosion, and replacing any wing lift 
strut where corrosion is found. The proposed AD would supersede AD 95-
26-18 with a new AD that would:
    <bullet> Retain the initial inspection and possible replacement 
requirements of AD 95-26-18;
    <bullet> Require the inspections to be repetitive; and
    <bullet> Provide the option of using ultrasonic procedures to 
accomplish the inspection requirements.
    Accomplishment of the actions required by AD 95-26-18 is in 
accordance with Maule Service Bulletin (SB) No. 11, dated October 30, 
1995.
    The NPRM was the result of a report of an accident where the wing 
separated from one of the affected airplanes.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were received on the 
proposed rule or the FAA's determination of the cost to the public.

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

[[Page 39019]]

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.

Compliance Time of This AD

    The compliance time of this AD is presented in calendar time 
instead of hours time-in-service. The FAA has determined that a 
calendar time for compliance is the most desirable method because the 
unsafe condition described in this AD is caused by corrosion. Corrosion 
can occur on airplanes regardless of whether the airplane is in 
service.

Cost Impact

    The FAA estimates that 1,196 airplanes in the U.S. registry will be 
affected by this AD, that it will take 11 workhours per airplane to 
accomplish the initial inspection, and that the average labor rate is 
approximately $60 an hour. Parts to accomplish the initial inspection 
cost approximately $40 per airplane. Based on these figures, the total 
cost impact of this AD on U.S. operators is estimated to be $837,200, 
or $700 per airplane. This figure only takes into account the cost of 
the initial inspection and does not take into account the cost of the 
repetitive inspections. The FAA has no way of determining how many 
repetitive inspections each owner/operator of the affected airplanes 
will incur.
    In addition, these figures are based upon the presumption that no 
affected airplane operator has accomplished the initial inspection, and 
does not take into account the cost for replacement if corrosion is 
found on a wing lift strut. The FAA has no way of determining the 
number of wing lift struts that may need to be replaced based upon the 
results of the inspections.

Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a 
significant economic impact, positive or negative, on a substantial 
number of small entities under the criteria of the Regulatory 
Flexibility Act. A copy of the final evaluation prepared for this 
action is contained in the Rules Docket. A copy of it may be obtained 
by contacting the Rules Docket at the location provided under the 
caption ADDRESSES.

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

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

PART 39--AIRWORTHINESS DIRECTIVES

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

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


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Airworthiness Directive 
(AD) 95-26-18, Amendment No. 39-9476 (61 FR 623, January 9, 1996), and 
by adding a new AD to read as follows:

98-15-18  Maule Aerospace Technology Corp.: Amendment 39-10669; 
Docket No. 98-CE-01-AD; Supersedes AD 95-26-18, Amendment 39-9476.

    Applicability: The following airplane models, all serial 
numbers, certificated in any category, that are equipped with part 
number (P/N) 2079E (or FAA-approved equivalent part number) rear 
wing lift struts or P/N 2080E (or FAA-approved equivalent part 
number) front wing lift struts:

Bee Dee                    M-4                        M-4C                      M-4S                            
M-4T                       M-4-180C                   M-4-180S                  M-4-180T                        
M-4-210                    M-4-210C                   M-4-210S                  M-4-210T                        
M-4-220                    M-4-220C                   M-4-220S                  M-4-220T                        
M-5-180C                   M-5-200                    M-5-210C                  M-5-210TC                       
M-5-220C                   M-5-235C                   M-6-180                   M-6-235                         
M-7-235                    MX-7-235                   MX-7-180                  MX-7-420                        
MXT-7-180                  MT-7-235                   M-8-235                   MX-7-160                        
MXT-7-160                  MX-7-180A                  MXT-7-180A                MX-7-180B                       
MXT-7-420                  M-7-235B                   M-7-235A                  M-7-235C                        
                                                                                                                

    Note 1: This AD does not apply to airplanes equipped with four 
Maule sealed lift struts, P/N 2200E and P/N 2201E. These sealed lift 
struts are identified by two raised weld spots on the upper end of 
the strut just below the serial number plate. Removal of the upper 
cuff is needed to locate the weld spots.
    Note 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 (e) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated in the body of this AD, unless 
already accomplished.
    To prevent failure of the wing lift struts caused by corrosion 
damage, which could eventually result in the wing separating from 
the airplane, accomplish the following:

    Note 3: The paragraph structure of this AD is as follows:

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

Level 2 and Level 3 structures are designations of the Level 1 
paragraph they immediately follow.
    (a) Upon accumulating 2 years on a lift strut affected by this 
AD; within 3 calendar months after the effective date of this AD; or 
within 2 years after the last inspection accomplished in accordance 
with AD 95-26-18 (superseded by this action), whichever occurs 
later, remove the wing lift struts in accordance with the 
INSTRUCTIONS section of Maule Service Bulletin (SB) No. 11, dated 
October 30, 1995, and accomplish one of the following (the actions 
in either paragraph (a)(1), (a)(2), (a)(3), or (a)(4), including all 
subparagraphs, of this AD):
    (1) Inspect the wing lift struts for corrosion in accordance 
with the INSPECTION

[[Page 39020]]

PROCEDURE section of Maule SB No. 11, dated October 30, 1995.
    (i) If no perceptible dents (as defined in the above SB) are 
found in the wing lift strut and no corrosion is externally visible, 
apply corrosion inhibitor to each strut in accordance with Maule SB 
No. 11, dated October 30, 1995. Reinspect the wing lift struts at 
intervals not to exceed 24 calendar months provided no perceptible 
dents or external corrosion is found.
    (ii) If a perceptible dent (as defined in the above SB) 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) 
and (a)(4) 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 or Level 3 inspector 
certified using the guidelines established by the American Society 
for Non-destructive Testing, or MIL-STD-410.
    (i) If no external corrosion is found and all requirements in 
the Appendix to this AD are met, prior to further flight, apply 
corrosion inhibitor to each strut in accordance with Maule SB No. 
11, dated October 30, 1995. Reinspect the lift struts at intervals 
not to exceed 24 calendar months provided no external corrosion is 
found and all of the requirements included in the Appendix of this 
AD are met.
    (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) 
and (a)(4) of this AD.
    (3) Install original equipment manufacturer (OEM) part number 
wing lift 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. Accomplish this installation in accordance with the 
applicable maintenance manual. 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 Maule sealed wing lift struts, P/N 2200E or P/N 
2201E, as applicable (or FAA-approved equivalent part numbers) on 
each wing as specified in the INSTRUCTIONS section in Part II of 
Maule SB No. 11, dated October 30, 1995.
    (b) If holes are drilled into the sealed wing lift strut 
assemblies installed as specified in paragraph (a)(4) of this AD in 
order 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 either paragraph (a)(1) or (a)(2), 
including all subparagraphs, of this AD.
    (c) The repetitive inspections required by this AD may be 
terminated after installing new wing lift strut assemblies as 
specified in paragraph (a)(4) of this AD provided no holes are 
drilled in these strut assemblies as specified in paragraph (b) of 
this AD.
    (d) Special flight permits may be issued in accordance with 
sections 21.197 and 21.197 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (e) An alternative method of compliance or adjustment of the 
initial or repetitive compliance times that provides an equivalent 
level of safety may be approved by the Manager, 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 95-26-18 are considered approved as alternative methods of 
compliance for this AD.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Atlanta ACO.

    (f) The removal, the lift strut inspection (in paragraph (a)(1) 
of this AD), the applications, and the installation required by this 
AD shall be done in accordance with Maule Service Bulletin No. 11, 
dated October 30, 1995. This incorporation by reference was 
previously approved by the Director of the Federal Register as of 
January 26, 1996 (61 FR 623, January 9, 1996). Copies may be 
obtained from Maule Aerospace Technology, Inc., 2099 GA Hwy. 133 
South, Moultrie, Georgia 31768. Copies may be inspected at the FAA, 
Central Region, Office of the Regional Counsel, Room 1558, 601 E. 
12th Street, Kansas City, Missouri, or at the Office of the Federal 
Register, 800 North Capitol Street, NW, suite 700, Washington, DC.
    (g) This amendment supersedes AD 95-26-18, Amendment 39-9476.
    (h) This amendment becomes effective on September 9, 1998.

Appendix to AD 98-15-18--Procedures and Requirements for Ultrasonic 
Inspection of Maule 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.

    <bullet> 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.''
    <bullet> 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

[[Page 39021]]

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 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.

    <bullet> 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.

    <bullet> 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.

[[Page 39022]]

[GRAPHIC] [TIFF OMITTED] TR21JY98.000



    Issued in Kansas City, Missouri, on July 14, 1998.
Marvin R. Nuss,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-19328 Filed 7-20-98; 8:45 am]
BILLING CODE 4910-13-P