DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-9550; Directorate Identifier 2016-CE-026-AD;
Amendment 39-18894; AD 2017-10-20]
RIN 2120-AA64

Airworthiness Directives; Piper Aircraft, Inc. Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain
Piper Aircraft, Inc. Models PA-31, PA-31-300, PA-31-325, and PA-31-350
airplanes. This AD was prompted by fatigue cracking in the fuselage
station (FS) 332.00 bulkhead common to the horizontal stabilizer front
spar attachment. This AD requires repetitive inspections to detect
cracks in the bulkhead and any necessary repairs. This AD also provides
an optional modification if no cracks are found that will greatly
reduce the likelihood of the specified cracks. We are issuing this AD
to correct the unsafe condition on these products.

DATES: This AD is effective June 29, 2017.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of June 29,
2017.

ADDRESSES: For service information identified in this final rule,
contact Piper Aircraft, Inc., Customer Service, 2926 Piper Drive, Vero
Beach, Florida 32960; telephone: (877) 879-0275; fax: none; email:
customer.service@piper.com; Internet: www.piper.com. You may view this
referenced service information at the FAA, Small Airplane Directorate,
901 Locust, Kansas City, Missouri 64106. For information on the
availability of this material at the FAA, call (816) 329-4148. It is
also available on the internet at http://www.regulations.gov by
searching for and locating Docket No. FAA-2016-9550.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov
by searching for and locating Docket No. FAA-2016-9550;
or in person at the Docket Management Facility between 9 a.m. and
5 p.m., Monday through Friday, except Federal holidays. The AD docket
contains this AD, the regulatory evaluation, any comments received, and other
information. The address for the Docket Office (phone: 800-647-5527) is Document Management Facility, U.S. Department of Transportation, Docket Operations, M-30,
West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE.,
Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Gregory "Keith" Noles, Aerospace
Engineer, FAA, Atlanta Aircraft Certification Office, 1701 Columbia
Avenue, College Park, Georgia 30337; phone: (404) 474-5551; fax: (404)
474-5606; email: gregory.noles@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR
part 39 by adding an AD that would apply to certain Piper Aircraft,
Inc. Models PA-31, PA-31-300, PA-31-325, and PA-31-350 airplanes. The
NPRM published in the Federal Register on January 3, 2017 (82 FR 48).
The NPRM was prompted by reports of fatigue cracking in the FS 332.00
bulkhead common to the horizontal stabilizer front spar attachment on
Piper Aircraft, Inc. PA-31 airplanes. Cracks in the bulkhead could
compromise the structural component's capability to carry flight loads,
increasing the potential to overload and fail adjacent structure. The
NPRM proposed to provide an optional modification if no cracks are
found that will greatly reduce the likelihood of the specified cracks.
We are issuing this AD to detect and repair cracks in the bulkhead that
could lead to structural failure and result in loss of control.

Comments

We gave the public the opportunity to participate in developing
this AD. The following presents the comments received on the NPRM and
the FAA's response to each comment.

Request Change to Labor Estimates

Joe M. Miller, Chief Inspector for Warbelow's Air Ventures, Inc. in
Fairbanks, Alaska, stated they have complied with the proposed
requirement on 3 airplanes and find that it takes 2 mechanics about 6
hours each (12 man-hours) to accomplish just the inspection phase. The
commenter states that to better access the affected areas it is easier
to remove both horizontal stabilizers. In total, it takes a crew of 2
about 4 days (64 man-hours) to accomplish the complete process from
inspection to return to service.
We partially agree. We agree with revising the labor estimates for
both the inspection and modification because of the additional operator
data. Also, we will ensure the access time is included in both the
inspection and modification estimates. Because the original time
estimate was provided by another experienced operator, we will update
the estimate to reflect an average of the two reported times. We
disagree with using a combined estimate of 64 hours because the
inspection and modification are estimated separately. We will make the
following changes to the AD based on this comment:
Update the inspection labor estimate from 1 hour to 12
hours; and
Update the modification labor estimate from 26 to 45
hours.

Question on Airplanes That Have Previously Complied

Joe M. Miller, Chief Inspector, Warbelow's Air Ventures, Inc.,
Fairbanks, Alaska, asked that we provide reference to those airplanes
that have previously complied with Service Bulletin 1289A and installed
kit 88578-001 Rev B. The commenter stated the NPRM only addresses the
initial inspection and modification of FS 332 and does not address
airplanes that have previously complied with Piper MSB 1289A by
inspection and subsequent installation of the Piper Kit 88578-001 Rev B.
We do not agree because paragraph (f) of the AD addresses this
situation with the phrase ``unless already done.''
We have not changed the AD based on this comment.

Request To Extend the Initial Compliance Time

Roger Braun asked that we extend the initial compliance time
because his impression is that the cracks were found solely on one very
high-time (20,000 hour plus) airplane, and he perceives 3,000 hours
time-in-service (TIS) as too early to start the inspection intervals
based on the finding.
We do not agree because the airplane design is intended to provide
a service life that is crack-free. When cracks are found in service, a
management program is put in place (reference Advisory Circular 91-82).
It is true that the crack was found on an airplane with over 20,000
hours. The compliance time for the management program is based on the
known failure time but must include safety and statistical reduction
factors (reference Advisory Circular 23-13). Starting inspections at
3,000 hours TIS ensures any cracks that form will be found early enough
to prevent an unsafe condition. While it may appear excessive, the
compliance time is set to meet the design intent of a crack-free
operation.
We have not changed the AD based on this comment.

Request for a Visual Inspection

Roger Braun asked that we allow for a visual inspection instead of
a penetrant inspection because the parts involve a simple visual
inspection. The commenter suggested that 10x glass would suffice
instead of stripping paint and doing a dye-penetrant inspection. Then,
a penetrant could be used if any cracks are suspected.
We do not agree because the cleaning and penetrant method has
higher detection reliability than a purely visual method. The
reliability of the inspection method is tied to the compliance time for
the repetitive inspection and deferral of the permanent modification.
Once the AD is published, the commenter may request an alternative
method of compliance (AMOC) for the visual inspection method. The
request, including all substantiating data, may be submitted following
14 CFR 39.19 as specified in paragraph (i)(1) of this AD.
We have not changed the AD based on this comment.

Clarification on Installation of the Kit

Tim Glubaskas, Director of Maintenance, Warbelow's Air Ventures,
asked for a clarification on whether installation of the kit terminates
the repetitive inspections.
That kit installation is terminating action for the repetitive
inspection. This is addressed in paragraph (g)(3)(i) of this AD when
the kit is used as a repair for cracks and in paragraph (g)(4) of this
AD when the kit is used as a modification with no cracks.
We have not changed the AD based on this comment.

Conclusion

We reviewed the relevant data, considered the comments received,
and determined that air safety and the public interest require adopting
this AD with the changes described previously and minor editorial
changes. We have determined that these changes:
Are consistent with the intent that was proposed in the
NPRM for correcting the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.
We also determined that these changes will not increase the
economic burden on any operator or increase the scope of this AD.

Related Service Information Under 1 CFR Part 51

We reviewed Piper Aircraft, Inc. Service Bulletin No. 1289A, dated
October 26, 2016. The service information describes procedures for the
repetitive inspections, necessary repairs, and the optional
modification of the bulkhead. This service information is reasonably
available because the interested parties have access to it through
their normal course of business or by the means identified in the
ADDRESSES section.

Costs of Compliance

We estimate that this AD affects 955 airplanes of U.S. registry.
We estimate the following costs to comply with this AD:

Estimated Costs

We estimate the following costs to do any necessary repairs/
replacements that would be required based on the results of the
inspection. We have no way of determining the number of airplanes that
might need these repairs/replacements:

On-Condition Costs

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
rulemaking action.

Regulatory Findings

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 DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979),
(3) Will not affect intrastate aviation in Alaska, and
(4) 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.

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 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. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive (AD):