Document ID: FAA-2018-1046-0180
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: Piper Aircraft, Inc. Airplanes
Posted Date: 2020-06-03T04:00Z

[Federal Register Volume 85, Number 107 (Wednesday, June 3, 2020)]
[Proposed Rules]
[Pages 34121-34136]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-11343]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2018-1046; Product Identifier 2018-CE-049-AD]
RIN 2120-AA64

Airworthiness Directives; Piper Aircraft, Inc. Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Supplemental notice of proposed rulemaking (SNPRM); reopening 
of comment period.

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SUMMARY: The FAA is revising an earlier proposal for certain Piper 
Aircraft, Inc. (Piper) Models PA-28-140, PA-28-150, PA-28-151, PA-28-
160, PA-28-161, PA-28-180, PA-28-181, PA-28-235, PA-28R-180, PA-28R-
200, PA-28R-201, PA-28R-201T, PA-28RT-201, PA-28RT-201T, PA-32-260, and 
PA-32-300 airplanes. The notice of proposed rulemaking (NPRM) was 
prompted by a report of a wing separation caused by fatigue cracking in 
a visually inaccessible area of the lower main wing spar cap. This 
action revises the NPRM by adding and removing certain models of 
airplanes in the Applicability, proposing to require the use of service 
information that was issued since the NPRM, and clarifying some of the 
proposed actions. The FAA is proposing this airworthiness directive 
(AD) to address the unsafe condition on these products. Since these 
actions would impose an additional burden over those proposed in the 
NPRM, the FAA is reopening the comment period to allow the public the 
chance to comment on these changes.

DATES: The comment period for the NPRM published in the Federal 
Register on December 21, 2018 (83 FR 65592), is reopened.
    The FAA must receive comments on this SNPRM by July 20, 2020.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE, Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE, Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    For service information identified in this SNPRM, Piper Aircraft, 
Inc., 2926 Piper Drive, Vero Beach, Florida 32960; telephone: (772) 
567-4361; internet: www.piper.com. You may view this service 
information at the FAA, Airworthiness Products Section, Operational 
Safety Branch, 901 Locust, Kansas City, Missouri 64106. For information 
on the availability of this material at the FAA, call (816) 329-4148.

Examining the AD Docket

    You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2018-
1046; or in person at Docket Operations between 9 a.m. and 5 p.m., 
Monday

[[Page 34122]]

through Friday, except Federal holidays. The AD docket contains this 
SNPRM, the NPRM, the regulatory evaluation, any comments received, and 
other information. The street address for Docket Operations is listed 
above. Comments will be available in the AD docket shortly after 
receipt.

FOR FURTHER INFORMATION CONTACT: Dan McCully, Aerospace Engineer, 
Atlanta ACO Branch, FAA, 1701 Columbia Avenue, College Park, Georgia 
30337; phone: (404) 474-5548; fax: (404) 474-5605; email: 
william.mccully@faa.gov.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2018-1046; 
Product Identifier 2018-CE-049-AD'' at the beginning of your comments. 
The FAA specifically invites comments on the overall regulatory, 
economic, environmental, and energy aspects of this SNPRM. The FAA will 
consider all comments received by the closing date and may amend this 
SNPRM because of those comments.
    The FAA will post all comments received, without change, to https://www.regulations.gov, including any personal information you provide. 
The FAA will also post a report summarizing each substantive verbal 
contact received about this SNPRM.

Discussion

    The FAA issued an NPRM to amend 14 CFR part 39 by adding an AD that 
would apply to certain Piper Aircraft, Inc. (Piper) Models PA-28-140, 
PA-28-150, PA-28-151, PA-28-160, PA-28-161, PA-28-180, PA-28-181, PA-
28-235, PA-28R-180, PA-28R-200, PA-28R-201, PA-28R-201T, PA-28RT-201, 
PA-28RT-201T, PA-32-260, and PA-32-300 airplanes. The NPRM published in 
the Federal Register on December 21, 2018 (83 FR 65592).
    The NPRM was prompted by a fatal accident involving wing separation 
on a Piper Model PA-28R-201 airplane. An investigation revealed a 
fatigue crack in a visually inaccessible area of the lower main wing 
spar cap. The NPRM included other model airplanes with similar wing 
spar structures as the Model PA-28R-201. Based on airplane usage 
history, the FAA determined that only those airplanes with higher risk 
for fatigue cracks (airplanes with a significant history of operation 
in flight training or other high-load environments) should be subject 
to the inspection requirements proposed in the NPRM.
    Because airplanes used in training and other high-load environments 
are typically operated for hire and have inspection programs that 
require 100-hour inspections, the FAA determined the number of 100-hour 
inspections an airplane has undergone would be the best indicator of 
the airplane's usage history. Accordingly, the FAA developed a factored 
service hours formula based on the number of 100-hour inspections 
completed on the airplane.
    The NPRM proposed to require a review of the airplane maintenance 
records to determine the number of 100-hour inspections and the 
application of the factored service hours formula to identify when an 
airplane meets the criteria for the proposed eddy current inspection of 
the lower main wing spar bolt holes. The NPRM also proposed to require 
inspecting the lower main wing spar bolt holes for cracks once a main 
wing spar exceeds the specified factored service hours and replacing 
any main wing spar when a crack is indicated. The maintenance records 
review to determine the factored service hours proposed by the NPRM 
would only apply when an airplane has either accumulated 5,000 or more 
hours time-in-service (TIS); has had either main wing spar replaced 
with a serviceable main wing spar (more than zero hours TIS); or has 
missing and/or incomplete maintenance records.

Actions Since the NPRM Was Issued

    After a review of the comments received on the NPRM and further 
analysis, the FAA determined that some additional airplane models are 
likely to be affected by the unsafe condition and should be included in 
the applicability, while other models are not affected and should be 
removed from the applicability. Consequently, this SNPRM revises the 
applicability and the estimated cost associated with the proposed AD 
actions. This SNPRM also clarifies the applicability and some of the 
proposed actions. In addition, this supplemental NPRM no longer allows 
replacement of the wing spar with a used part. The FAA determined 
replacement of the wing spar with a part of unknown operational history 
would not ensure an acceptable level of safety.
    Since the NPRM was issued, Piper issued a service bulletin that 
contains procedures for the eddy current inspection. This SNPRM 
proposes to require that service bulletin to do the eddy current 
inspection instead of the inspection procedure in the appendix to the 
NPRM.
    Since these actions impose an additional burden over that in the 
NPRM, the FAA is reopening the comment period to allow the public the 
chance to comment on this change.

Comments

    The FAA gave the public the opportunity to comment on the NPRM and 
received approximately 168 comments. The majority of the commenters 
were individual maintenance personnel and operators. The remaining 
commenters included Piper, governmental agencies such as the European 
Union Aviation Safety Agency (EASA) and the National Transportation 
Safety Board (NTSB), and organizations such as the Aircraft Owners and 
Pilots Association (AOPA), the Experimental Aircraft Association (EAA), 
and the General Aviation Manufacturers Association (GAMA). The 
following presents the relevant comments received on the NPRM and the 
FAA's response to each comment.

A. Supportive Comments

    Fifteen comments were received in support of the NPRM. Five of 
these commenters specifically supported the proposed eddy current 
inspection method. The NTSB specifically supported the proposed 
requirement to report inspection results to the FAA.

B. Comments Regarding the FAA's Justification of the Unsafe Condition

    Many commenters requested that the FAA provide more information 
about the root cause and clarify the FAA's unsafe condition 
determination.
Requests for Information About the Accident Airplane
    Mitchell Ross requested information regarding the background of the 
accident airplane that prompted the NPRM, including its manufacturing 
and maintenance history. This commenter and Robert Cunningham also 
questioned the operational history of the accident airplane. Nine other 
commenters questioned the FAA's determination that an unsafe condition 
exists based on only one failure in 30 years.
    The FAA agrees. All publicly available information about the 
accident airplane, including the information requested by the 
commenters, is available in the NTSB docket for accident number 
ERA18FA120. This information can be viewed at https://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=62694&CFID=95094&CFTOKEN=b616b3892cb482f1-5B544A63-5056-942C-92C71C2E6BFF1D97.

[[Page 34123]]

Requests for Information About the Root Cause of the Unsafe Condition
    David Hedley and Dana Pyle noted that Piper's steel supplier 
changed in the 1980s. These commenters and Robert Cunningham questioned 
whether inferior metal could be a factor. Tom McIntosh, Dana Pyle, and 
Robert Cunningham questioned whether coastal environments contributed 
to the corrosion and metal fatigue. Steven Rosenfield asked the FAA to 
confirm whether the fatigue cracking is caused by a design defect or a 
manufacturing error. Some commenters suggested that the problem is 
caused by other issues such as inadequate inspection and maintenance 
practices, and hard landings that go unreported.
    The FAA agrees to provide additional information. The NTSB 
Materials Laboratory conducted hardness testing and electrical 
conductivity testing of the accident spar and sent spar samples to an 
independent laboratory for tension testing and chemical analysis. Tests 
results showed that the spar material conformed to type design (see 
NTSB report No. 18-061, Materials Laboratory Factual Report). Corrosion 
was not determined to be a contributing factor. Regarding the concern 
about inadequate inspections and maintenance practices, the NTSB report 
did not indicate there was any evidence of inadequate inspection and 
maintenance practices.
Request To Reference the Piper Model PA-28R-201 Accident
    AOPA noted the absence of any specific mention of the April 4, 
2018, Piper PA-28R-201 accident (NTSB Accident Number ERA18FA120) in 
the NPRM. The commenter stated its belief that the accident is a 
driving force behind the NPRM.
    The FAA agrees. The preamble of this SNPRM has been revised to add 
information related to the accident.
Requests To Wait for NTSB Final Report Before Issuing AD Action
    Joseph Oh, The University of North Dakota (UND Aerospace), AOPA, 
Navid Rahimi, Benjamin Morgan, and eight other commenters requested the 
FAA wait for the conclusion of the NTSB investigation before issuing an 
AD. These commenters stated or suggested that the proposed AD is 
premature and that the NTSB's determinations would affect the content 
or necessity of the proposed AD. Piper stated that the proposed AD 
would likely interfere with the NTSB's investigation. Some of these 
commenters specifically referenced the NTSB's investigation of a Piper 
Model PA-28R-201 Arrow III that experienced an in-flight wing 
separation on April 4, 2018.
    The FAA does not agree. In accordance with 14 CFR 39.5, the FAA 
issues airworthiness directives when an unsafe condition exists in the 
product, and the condition is likely to exist or develop in other 
products of the same type design. While the NTSB contributes critical 
information to accident prevention efforts, the FAA's determinations of 
unsafe conditions are not dependent on the outcome of NTSB 
investigations. The FAA, Piper, and the NTSB concurred that the subject 
failure was the result of an undetected fatigue crack in the wing spar. 
This was supported by the NTSB's release of Preliminary Report 
ERA18FA120 and a later Investigative Update, which disclosed additional 
fatigue cracks on another airplane. Although the NTSB's final report 
(issued after the NPRM published) provides additional details regarding 
the accident, it does not yield information previously unknown to the 
FAA that would have altered the content of the NPRM, nor did the NTSB 
request the FAA delay issuing the NPRM pending its final report. The 
NTSB reports may be found at https://www.ntsb.gov/investigations/pages/era18fa120.aspx. The FAA did not make changes to this SNPRM based on 
these comments.
Request To Withdraw the NPRM
    Dwight Schrute, Ross Carbiner, Thomas Feminella, AOPA, EAA, GAMA, 
Piper, and 21 other commenters stated that because the AD was issued as 
an interim action with a reporting requirement, the AD is inappropriate 
and does not address a known unsafe condition. Nine of those commenters 
stated that a special advisory information bulletin (SAIB), service 
bulletin, or other voluntary action is a more appropriate method of 
addressing the wing spar fatigue cracking. Four of those commenters 
opposed the AD generally. Michael Powell did not request to withdraw 
the NPRM, but suggested the FAA obtain information from DeHaviland 
Support, because this company has experience with a relevant wing spar 
fatigue monitoring scheme that has been implemented for the DeHaviland 
Model Chipmunk airplanes. Three other commenters suggested the FAA 
gather data from voluntary inspections and salvage parts before issuing 
an AD.
    The FAA does not agree to withdraw the NPRM. The FAA may issue an 
AD as an interim action for several reasons, including to obtain 
inspection results to determine the necessity of additional action or 
final action, while simultaneously requiring inspections to mitigate 
the unsafe condition. The primary considerations in reaching the 
decision for an interim AD were: (1) The catastrophic failure mode 
resulting from this condition, and (2) the inability to detect the 
subject cracking during a routine inspection. The NTSB accident 
database shows a relatively small number of Piper Model PA-28 airplane 
wing failures related to fatigue cracks (three known). However, the 
only reported cracks were discovered after wing separations, since the 
cracks developed and grew in a normally concealed structural area. In 
addition, it can be predicted based on engineering priniciples of crack 
propagation that a fatigue crack in this location will grow with each 
load cycle and eventually result in wing spar failure. Due to the 
fatality rate associated with the known failures, the risk analysis 
protocol used by the FAA justifies mandatory corrective action. Both 
the NPRM and this SNPRM employ methodology to screen out the majority 
of lower-risk airplanes based on usage history. The FAA did not make 
changes to this SNPRM based on these comments.

C. Comments Regarding Applicability

Requests To Revise the Airplane Models Listed in the Applicability 
Section
    Piper, EAA, and GAMA stated that the applicability of the proposed 
AD is too broad and includes models with different structural layouts 
and loads, or other key aspects that affect spar fatigue. Piper 
specifically advised the FAA to rely on Piper's analysis and limit the 
proposed AD to Piper Models PA-28R-180, PA-28R-200, PA-28R-201, PA-28R-
201T, PA-28RT-201, PA-28RT-201T, and PA-28-235 airplanes (all serial 
numbers), and certain serial-numbered Models PA-32-260 and PA-32-300 
airplanes. Eight other commenters agreed with the comments submitted by 
Piper. AOPA and two individual commenters expressed concern that the 
FAA did not accept Piper's recommendation on the limited scope of 
airplanes that may be subject to the unsafe condition. The NTSB 
supported the inclusion of Models PA-28-235, all PA-28R-series, PA-32-
260, and PA-32-300 airplanes in the proposed AD, and requested that the 
FAA reconsider whether the proposed AD should include all PA-28-series 
models (other than Model PA-28-235).
    Thomas Rae identified Piper model seaplanes and airplanes that, 
given their similar structure, hours in service, and/or use in flight 
training, should be added to the Applicability section of the proposed 
AD. Twelve other commenters

[[Page 34124]]

requested the FAA clarify the inclusion or exclusion of various 
specific models. Charles Martinak stated wingspan, maximum gross 
takeoff weight, and retractable gear architecture should be the main 
similarity factors for inclusion in the applicability.
    The FAA agrees that the models listed in the Applicability of the 
proposed AD should be revised. The Applicability section was designed 
to screen out lower-risk airplanes from the inspection requirement by 
applying only to airplanes with 5,000 or more hours TIS, unless 
maintenance records are missing and/or incomplete or a wing has been 
replaced. The subsequent maintenance records review to calculate 
factored service hours was intended to eliminate an additional large 
number of remaining airplanes from the AD requirements. Only the 
airplanes at the highest risk for fatigue cracks would be required to 
conduct the eddy current inspection.
    Piper Aircraft provided the FAA with extensive analyses of 
similarly structured airplanes, including comparison of factors such as 
structural geometry, certificated weights, design airspeeds, bending 
moments, and wing loading parameters including gust loads, maneuvering 
loads, and landing loads. Although the FAA accepted all of Piper's 
initial recommended models for effectivity, Piper's recommended 
effectivity did not include the group of airplanes addressed in Piper 
Aircraft, Inc. Service Bulletin No. 886, dated June 8, 1988 (Piper SB 
886) (Wing Spar Inspection). Piper SB 886 includes the Model PA-28-181 
airplane, which was involved in two wing separation accidents in 1987 
and 1993. Both accident airplanes had fatigue cracks in the wing spar 
as mentioned in the NTSB Final Accident Report ERA18FA120.
    Due to the inability to visually inspect the specific area of the 
structure once the wing has been assembled, cracks may go undetected 
and unreported for a significant period of time. Consequently, a 
reported crack at this location is more likely to come from an 
investigation of a wing spar failure than as the result of a routine 
inspection or maintenance. The FAA initially expanded on Piper's 
recommended effectivity to include all airplane models in the 
Applicability section of Piper SB 886.
    Since issuing the NPRM, and partially in response to public 
comments, the FAA has adopted a more focused risk criteria using load 
data provided by Piper. This risk approach and the resulting change in 
applicability adds three airplane models (Models PA-32R-300, PA-32RT-
300, and PA-32RT-300T) and removes five airplane models (Models PA-28-
140, PA-28-150, PA-28-160, PA-28-161, and PA-28-180) from the 
Applicability section of this SNPRM, for a net reduction of 
approximately 8,800 lower-risk aircraft. The FAA developed a more 
precise methodology for identifying risk. Flight loads of all similar 
models were compared to those of the PA-28R-201 (accident aircraft) as 
a baseline. Those aircraft models with calculated wing loads greater 
than or equal to 95 percent of baseline are considered at-risk and are 
included in the new effectivity. While the additional parameters 
included in the new screening method allowed us to remove many lower 
risk aircraft, it also identified three models that were not captured 
by the previous, broader, approach. Because this methodology considers 
only the potential damage to the aircraft and not the actual load 
history of an individual aircraft, the additional maintenance record 
reviews are used to determine when the AD becomes applicable to a 
specific aircraft.

D. Comments Regarding the ``Factored Service Hours'' Formula

Requests To Clarify and Revise the ``Factored Service Hours'' Formula
    Floris Oldenbroek, Richard Davis, and three other commenters 
expressed confusion at the formula and requested clarification and 
guidance; two of these commenters specifically asked about the divisor 
``17.'' Many commenters noted various flaws in the proposed methodology 
for counting 100-hour inspections. Tom Rafferty, Kenneth Minck, Brian 
Christie, and approximately 19 other commenters stated maintainers 
often document 100-hour inspections as ``annual'' inspections or as 
``annual/100-hour'' inspections. EASA, AOPA, and three individual 
commenters stated that the formula would cause issues with 
international operators because, unlike the FAA's regulations, foreign 
civil aviation authorities do not distinguish between 100-hour and 
annual inspections. Several other commenters noted that using 100-hour 
inspections is not an accurate way of determining high stress flight 
hours. GAMA and five individual commenters noted that the formula does 
not address operators that are on a progressive inspection program 
under 14 CFR 91.409(d). Outer Banks Airlines and three individual 
commenters stated that not all commercial operations, which will be 
captured by counting 100-hour inspections, are used for flight 
instruction. These commenters explained that charter flights operated 
under 14 CFR part 135 are not subject to the harsh training environment 
of training operations and are instead flown by highly trained pilots 
on longer flights with fewer landings.
    Many of the commenters proposed different methodologies to use in 
determining the factored service hours. Chris Sobers, Thomas Downey, 
and three other commenters suggested using total time on the airframe 
(``TTAF'') as a less complex method. Floris Oldenbroek asked whether 
the total time of the aircraft could be used instead of the factored 
service hours formula if an airplane has only been utilized as a 
trainer. Martin Kennett and Lawrence Mangus suggested using the number 
of landing cycles/severe landings as a better indication of fatigue 
damage. Suggestions from other commenters included: Omitting 100-hour 
inspections performed in conjunction with an annual inspection; 
omitting 100-hour inspections performed voluntarily and not required by 
Sec.  91.409(b); using a severity factor to indicate primary use in 
flight training; only including airplanes used by flights schools/
excluding airplanes with no history of use in training; and adding a 
penalty for hard landings and major wing damage.
    The FAA agrees to explain the formula based on these comments. The 
FAA developed the factored service hours formula to determine an 
approximate factored service life for any airplane, including those 
with mixed usage history. The formula attributes 100 factored service 
hours for each 100-hour inspection recorded in the airplane maintenance 
records. For an airplane that has been inspected under Sec.  91.409(b) 
for its entire lifecycle, the owner/operator may use hours TIS for the 
factored service hours. The divisor of 17 accounts for the difference 
in structural life expectancy between ``normal'' use and ``training'' 
use, based on industry studies of crack growth development. Piper 
adopted a similar formula for use in Piper SB 886 and Piper Service 
Bulletin SB 978A, dated August 6, 1999 (Piper SB 978A).
    This SNPRM includes guidance for determining the quantity ``N'' in 
the factored service hours formula based on the various maintenance 
record entry notations that may be used to indicate compliance with the 
100-hour inspection requirements. As proposed in this SNPRM, the 
airplane maintenance records review must consider any inspection that 
was done to comply with the 100-hour inspection requirement under Sec.  
91.409(b), which pertains to carrying persons for hire and providing 
flight instruction for hire.

[[Page 34125]]

Regardless of whether the inspection is logged as an ``annual'' or 
``100-hour,'' if the purpose was to comply with the 100-hour 
requirement of Sec.  91.409(b), then the inspection must be counted. 
The purpose of an inspection may be determined by noting the interval 
between inspections (i.e., less than 10 months and typically from 90 to 
110 flight hours would indicate a Part 91.409(b) inspection). A ``100-
hour'' inspection done concurrently with an annual inspection, not 
required by Sec.  91.409(b), does not have to be counted. For operators 
utilizing a ``progressive'' inspection program, only inspections that 
complete each 100-hour cycle must be counted as a 100-hour inspection.
    The FAA has considered the impact of the proposed formula on 
international operators and agrees with EASA that civil airworthiness 
authorities (CAAs) would have to develop a different approach instead 
of fully adopting the FAA's AD. The FAA encourages CAAs to use their 
equivalent inspection requirements to account for differences in 
terminology relative to annual versus 100-hour inspections and other 
unique operational requirements. The FAA is available to support any 
such efforts as requested by a CAA.
    The FAA has also considered the alternative methods suggested by 
the commenters and determined that the formula in this SNPRM is the 
best method for allowing personal-use airplanes to defer the 
inspection. Using TTAF or TIS alone would not account for different 
types of usage history. Other commenters' proposals, while logical and 
valid, are not based on regulatory recordkeeping requirements and 
therefore would create other difficulties for owners and operators. For 
example, while use and history specifically in flight training, landing 
cycles, and hard landings are valid indicators, there is no regulatory 
requirement for U.S. operators to maintain such records, particularly 
for personal use airplane maintenance records. The FAA considered 
adding a penalty for any history of major repairs to the wing, but 
determined it would not be necessary. Any cracks, as well as other 
damage, would be detected and corrected during the repair to the wing, 
as the FAA's maintenance regulations require restoring the wing to its 
original or properly altered condition before approving it for return 
to service. In addition, any operator that believes their airplane does 
not fit the applicability/risk focus of this SNPRM may provide 
substantiating data and request approval of an alternative method of 
compliance (AMOC) to the AD action using the instructions found in 
paragraph (o) of this AD. The FAA will consider all AMOC requests on a 
case-by-case basis.
Request for Clarification of When To Calculate Factored Service Hours
    Mark Talaga requested clarification on the correct hours to require 
the eddy current inspection, 5,000 hours TIS or 5,000 factored service 
hours. Richard Davis asked the FAA to clarify why the records review 
would be done when the airplane has 5,000 hours TIS and not 6,000 hours 
TIS.
    The FAA agrees to provide additional information on this proposed 
requirement. The applicability paragraph of the NPRM referenced a table 
listing the potentially affected models and serial-numbered airplanes. 
It also provided three criteria to determine if the AD applied to the 
models listed in the table: (1) The airplane has accumulated 5,000 or 
more hours TIS; (2) the airplane has had either main wing spar replaced 
with a serviceable main wing spar (more than zero hours TIS); or (3) 
the airplane maintenance records are missing and/or incomplete.
    The 5,000 hours TIS criteria in paragraph (c), Applicability, is 
only used to determine if the AD applies to the airplane. If the 
airplane does not meet any of the three criteria, then the AD does not 
yet apply to that airplane. Only if and when one of those three 
conditions exist would the proposed AD require an airplane maintenance 
records review to determine the factored service hours. Then, only if 
the resulting calculation determines that the airplane has reached 
5,000 factored service hours must an eddy current inspection be 
completed within 100 hours TIS.
    The 5,000 factored service hours compliance time is determined by 
taking the known factored hours at spar failure, and regressing to 
predict the time of crack initiation. Starting the inspection at 5,000 
factored service hours provides a reasonable opportunity to detect a 
crack before it reaches a dangerous length. Because it is impossible 
for an aircraft to accumulate 5,000 factored service hours without 
having flown 5,000 hours TIS, there is no need to review an airplane's 
inspection record before 5,000 hours TIS.
Request To Change Quantity of 100-Hour Inspections Used in the 
Calculation
    John Longley requested limiting the 100-hour inspection calculation 
to the past 5, 7, or at most 10 years rather than since the airplane 
was new.
    The FAA disagrees. The effect of fatigue on a structure is 
cumulative regardless of when it occurred. The factored service hours 
formula takes into account airplanes with mixed usage history and 
provides credit for hours TIS accrued while in ``normal'' usage. The 
FAA did not make changes to this SNPRM based on this comment.
Request To Allow the Owner/Operator To Review the Airplane Maintenance 
Records
    Tom McIntosh, Dennis Mulloy, and four other commenters requested 
that the owner/operator be allowed to review the airplane maintenance 
records and calculate the factored service hours. These commenters 
objected to the cost associated with requiring a mechanic to do the 
airplane maintenance record review, when the owner/operator is capable.
    The FAA agrees. The FAA does not consider an airplane maintenance 
records review to be a maintenance action, and the SNPRM has been 
clarified to state that the owner/operator (pilot) may conduct the 
review and calculate the factored service hours to determine if the 
eddy current inspection proposed by this SNPRM is necessary. The 
airplane maintenance records review cost estimate has been retained in 
this SNPRM, since owners may choose to have a mechanic perform the 
initial review and factored service hours calculation.

E. Comments Regarding Missing Records

Requests for Clarification of Missing Aircraft Maintenance Records
    Dennis Mulloy requested clarification of what would constitute 
missing or incomplete maintenance records. James Layton asked for 
guidance where logbook entries may be missing but the airplane has 
verifiable hours through the original tachometer. Michael Beasley 
requested clarification for missing logbooks that are reconstructed by 
the maintenance facility that serviced the airplane.
    The FAA agrees to provide clarification. The premise of calculating 
factored service hours to determine the risk category of an airplane is 
based on the accuracy and completeness of the airplane maintenance 
records for the entire history of the airplane. An absence of airplane 
maintenance records entries over an extended period (as in the case of 
dormant airplanes) does not constitute missing or incomplete 
maintenance records if tachometer/Hobbs time continuity shows the 
airplane did not operate during that

[[Page 34126]]

time. For purposes of this proposed AD, reconstructed records should be 
considered the same as missing or incomplete records. Physically 
missing airplane maintenance records or logbook pages that include 
unaccounted-for operational hours or records not retained after work is 
superseded in accordance with 14 CFR 91.417(b)(1), would be considered 
missing or incomplete maintenance records.
Requests for an Alternative Method for Missing Aircraft Maintenance 
Records
    Michael Graziano, Duke Ball, Stephen Allen, and Olmond Hall 
requested that for airplanes with missing or incomplete maintenance 
records, operators be allowed to assume that 100-hour inspections were 
completed for the purposes of calculating the factored service hours, 
instead of being automatically required to complete the eddy current 
inspection. Four other commenters proposed or requested similar methods 
for attributing unknown hours TIS.
    The FAA disagrees. While the FAA does not object in theory with an 
alternate method of computing factored service hours in the case of 
missing airplane maintenance records, there are other issues to 
consider. Missing airplane maintenance records may mask the replacement 
of a tachometer or Hobbs meter, thus invalidating the total hours TIS. 
Missing records may hide information on the history of the wing/wing 
spar on the airplane. Without airplane maintenance records for the 
entire airplane's history, an operator cannot determine if the airplane 
has the original wing(s) or a replacement wing(s). For this reason, the 
FAA determined that, for purposes of this proposed AD, operators with 
missing or incomplete records must assume that the wing history is 
unknown. An owner who can provide other documentation supporting the 
history of the airplane or wing spar and show an acceptable level of 
safety may request approval of an AMOC to the AD action with 
substantiating data using the instructions found in paragraph (o) of 
this SNPRM. The FAA will review all AMOC requests and may approved the 
requests on a case-by-case basis. The FAA did not make changes to this 
SNPRM based on these comments.

F. Comments Regarding Compliance Times

    Thurman Bodenheimer, Christian Quitntero, and three other 
commenters requested that the compliance times and intervals in the 
NPRM be changed to match the airplane usage groups and intervals 
contained in Piper SB 886 and Piper SB 978A.
    The FAA disagrees. Piper SB 886 and Piper SB 978A classify 
airplanes used in flight training as ``normal usage,'' which puts 
compliance for the initial inspection far beyond the initial (critical) 
inspection time specified in the NPRM. The FAA has found that this 
compliance time is not sufficient to address the unsafe condition. 
Additionally, the compliance time charts in Piper SB 886 and Piper SB 
978A specify the airplane's usage class based on subjective criteria 
such as ``significant time'' flown below 1,000 feet during any part of 
the airplane's history. There is no regulatory requirement for 
operators to record or maintain hours TIS by operation at certain 
altitudes; thus, most operators would have no way of determining this 
information.
    Hillel Glazer proposed a specific tiered approach for compliance 
with the initial airplane maintenance records review by prioritizing 
airplanes based on usage history, with the lowest tier requiring the 
airplane maintenance record review within 100 hours TIS. Michael 
Graziano requested changing the compliance time from 30 days to 50 
hours TIS or at the next annual inspection, similar the service 
information provided by Piper. The FAA disagrees. The usage rate of 
each airplane after the effective date of the AD will vary, and the use 
of calendar time ensures all operators review their maintenance records 
within a specified timeframe. Also, this SNPRM has been revised to 
allow the owner/operator (pilot) to do the maintenance records review. 
If the review of the maintenance records and the factored service hours 
indicate the operator must have an eddy current inspection done on the 
airplane, the compliance time is within 100 hours TIS after the 
factored service hours determination.
    The FAA did not make changes to this SNPRM based on these comments.

G. Comments Regarding the Proposed Inspection

Requests To Remove Eddy Current Inspection Because of Possible Damage
    Daniel Stanley, Thomas Wiedenbeck, Mitchell Ross, Dana Pyle, Don 
Morris, Piper, and 17 other commenters stated that removal of wing 
attach bolts for the purpose of conducting the bolt hole inspection 
would create the potential of maintenance-induced damage to the 
airplanes that would outweigh any benefits realized from the 
inspection. Piper advised of reports of damaged spar bolt holes caused 
by removal of the bolts to perform a voluntary inspection of the 
fastener holes.
    The FAA disagrees. Compliance with AD 87-08-08, Amendment 39-5615 
(52 FR 15302, April 28, 1987) (``AD 87-08-08'') and AD 87-08-08R1, 
Amendment 39-5669 (52 FR 29505, August 10, 1987), which was rescinded 
on May 22, 1989, resulted in the dye penetrant inspection of 
approximately 560 airplanes and required removing and reinstalling 18 
bolts per wing, or over 20,000 wing attach bolts. No known accidents 
have been attributed to bolt hole damage resulting from these 
inspections. While the FAA acknowledges the possibility of damage 
during any maintenance action, the relatively non-intrusive, wing-in-
place inspection method proposed in the NPRM and in this SNPRM would 
have minimal impact to affected airplanes. The FAA did not make changes 
to this SNPRM based on these comments.
Requests To Use a Different Inspection Method
    Forrest Benson, Charles Donnelly, James Graham, and twelve other 
commenters proposed using a different inspection method than an eddy 
current inspection, such as ultrasound, x-ray, dye/liquid penetrant, or 
borescope inspections. Some of these commenters proposed using a 
borescope because it would preclude removal of the bolts. Many 
commenters expressed concern about the availability of qualified 
inspectors to do the eddy current inspection and the need to deliver 
the airplane to a distant facility to have the eddy current inspection 
done.
    The FAA disagrees. Borescope and dye penetrant methods are not 
generally capable of detecting cracks in the targeted range of .030 to 
.050 inch. Once a fatigue crack reaches a visibly detectable size, 
growth can accelerate at a dangerous rate. It is imperative that 
operators identify any cracks while within the targeted range. Also, 
because the lower spar cap sits on the spar carry through and its upper 
flanges are covered by the web doublers, the spar cap is not visually 
inspectable when installed. The insides of the bolt holes are not 
visible with a borescope inside the wing carry-through assembly without 
removing the bolts. While the FAA acknowledges the value of x-ray 
technology and ultrasound inspections in material identification and 
thickness determination, those methods are not considered capable of 
reliably detecting very small fatigue cracks. Changes made to the 
proposed AD in response to other comments will increase the 
availability of inspectors qualified to do the eddy current 
inspections. The FAA did not

[[Page 34127]]

make additional changes to this SNPRM as a result of these comments.
Requests To Use a Different Eddy Current Inspection Method and 
Equipment
    Tony Brand submitted an eddy current inspection procedure and 
requested approval to use this method as an alternative method of 
compliance. John Longley, Jr. requested that the eddy current 
inspection not require specific proprietary equipment. The FAA agrees 
that alternate eddy current methods may be acceptable. For any owner/
operator who wishes to use a different procedure, the FAA will consider 
requests for approval of an AMOC if sufficient data is submitted to 
substantiate that it would provide an acceptable level of safety, using 
the instructions in paragraph (o) of this AD. The FAA will consider all 
AMOC requests on a case-by-case basis.
    Neither the NPRM, nor this SPNRM, propose to require the use of any 
particular model equipment. The NPRM and Piper Service Bulletin No. 
1345, dated March 3, 2020, which this SNPRM proposes to incorporate by 
reference, contain optional examples of equipment that meet the 
requirements for conducting the eddy current inspection.
Requests for Clarification of Bolt Hole Inspection
    EASA requested clarification on the bolt holes to be inspected. 
EASA stated that Piper's service bulletins specify inspecting a larger 
area of the lower spar cap and asked whether inspecting only the two 
outboard holes, as proposed in the NPRM, is adequate. Blue Skies Flying 
Services requested clarification on the difference between the proposed 
inspection procedure in appendix 1 of the NPRM, which refers to only 
the two lower outboard bolt holes, and the proposed requirement to 
perform an eddy current inspection in paragraph (h) of the NPRM, which 
refers to each bolt hole on the lower main wing spar cap.
    The FAA agrees to clarify and revise the proposed requirement. The 
FAA has determined that the requirements in the NPRM to inspect only 
the two lower outboard bolt holes are adequate. The FAA has not 
observed a pattern of cracking at other spar hole locations and has not 
determined the benefit of inspecting additional holes would outweigh 
the potential of damage from bolt removal. The FAA has revised the 
proposed inspection requirements in this SNPRM to specify the two lower 
outboard bolt holes.
Requests To Expand the Eddy Current Inspection Qualifications
    Samuel Tucker, Norman Jones, and Humphrey Penney requested the 
proposed requirement for NAS 410 Level II or Level III qualifications 
to perform the eddy current inspection be expanded to include 
equivalent certifications.
    The FAA agrees. The FAA has revised the proposed AD to allow Level 
II or Level III qualification standards for inspection personnel using 
any of the inspector criteria approved by the FAA to conduct the eddy 
current inspection. This proposed change would increase the 
availability of inspectors qualified to do the eddy current 
inspections.
Requests To Clarify/Develop Additional Actions
    Mark Morris, Tony Brand, Michael Graziano, and Michael Beasley 
requested information about recurring inspection requirements 
associated with the NPRM. Forrest Benson asked whether the FAA and 
Piper could develop a doubler repair instead of requiring replacement 
of the spar due to parts unavailability. William Johnson noted that the 
only permanent solution would be to produce a spar strap or reinforcing 
plate. The FAA agrees to provide additional information related to 
follow-on actions that may be associated with this proposed AD. As a 
proposed interim action, this SNPRM would require a one-time inspection 
for cracks and a reporting requirement. The FAA will evaluate the 
results of the reports to determine if mandating terminating or 
repetitive action is warranted. The FAA and Piper have discussed 
possible contingent repetitive and terminating actions and determined 
that a doubler repair is not a practical repair solution at this time.
Requests To Add Aft Wing Attach Fitting Inspection
    Steven Ells and Pascal Robitaille expressed concern over the 
integrity of the aft spar attach point as a contributing factor to the 
fatigue cracking. These commenters requested including an inspection of 
the aft wing attach fitting for excessive play as a step in the NPRM 
and, if movement is detected, then performing the proposed eddy current 
inspection. John Henry described experiences with the aft spar attach 
and suggested criteria for a mandatory inspection.
    The FAA acknowledges that the integrity of the forward and aft wing 
spar attach points are relevant to loads imparted into the wing spar, 
but the FAA disagrees with adding an inspection of the wing spar attach 
points to this SNPRM. There is insufficient evidence to conclude that 
the forward or aft wing spar attach points have contributed to the 
unsafe condition addressed in this SNPRM. The FAA did not change this 
SNPRM as a result of these comments.
Requests Regarding the Installation of Access Panels
    David Sampson and Gerald Brown expressed concern that the NPRM 
fails to address that holes have to be cut in the wing skin and access 
panels installed to access the inspection area.
    The FAA disagrees. The eddy current inspection proposed by the NPRM 
does not require installing holes or access panels. The FAA did not 
make changes to this SNPRM as a result of this comment.

H. Comment Regarding the Reporting Requirement

    GAMA requested that the FAA revise the proposed AD to require 
reporting inspection results to both the FAA and to Piper, the type 
certificate holder.
    The FAA agrees and has revised this SNPRM accordingly.

I. Comments Regarding Credit for Previous Maintenance Actions

    Bryan Russell, Mark Maxwell, Art Sebesta, and Charles Martinak 
asked for credit for airplanes that have previously complied with AD 
87-08-08, Piper SB 886, or Piper SB 978A, which specified removal of 
both wings and dye penetrant inspection of all main spar attach bolts.
    The FAA disagrees. Dye penetrant inspection methods are not 
generally capable of detecting cracks in the targeted range of .030 to 
.050 inch. Additionally, the FAA is aware of one wing spar failure on 
an airplane after having undergone the dye penetrant inspection 
required by AD 87-08-08.
    Barry Roberts and Mark Womack requested credit for airplanes with a 
wing that has been replaced with a serviceable wing (over zero hours 
TIS) with a documented service history. Daniel Stanley stating that the 
proposed AD should not be required on airplanes that had a wing 
replaced 40 years ago with a low time wing. (The commenter did not 
state whether the documented wing history was available.)
    The FAA disagrees. Replacement wings (over zero hours TIS) that do 
not have a complete documented history raise the same considerations as 
missing airplane maintenance records. For a documented serviceable wing 
with less than 5,000 factored service hours, an owner/operator who can 
provide

[[Page 34128]]

documentation supporting the history of the airplane or wing spar and 
show an acceptable level of safety may provide substantiating data and 
request approval of an AMOC using the instructions found in paragraph 
(o) of this AD. The FAA will consider all AMOC requests on a case-by-
case basis. The FAA did not make changes to this SNPRM based on these 
comments.

J. Comments Regarding Special Flight Permits

    Thomas Feminella requested that the proposed AD allow a one-time 
ferry flight, because eddy current inspection facilities are scarce, 
many owners may fly their airplanes somewhere away from their base to 
get the inspection done, and if the wings fail the inspection the 
airplane may be trapped at a location where no major repairs are 
available. Charles Martinak also expressed concern of being grounded 
after flying to a distant facility for testing, which may or may not 
have repair capability.
    The FAA disagrees. Once a crack in the wing spar area reaches a 
detectable size, growth becomes rapid. The FAA does not allow ferry 
flights with known cracks in primary structures. However, the FAA has 
changed the inspector requirements, which will increase the number of 
available inspectors. The FAA did not make additional changes based on 
these comments.

K. Comments Regarding the Costs of Compliance

    AOPA and nine individual commenters stated generally that the 
estimated costs of the proposed AD are incorrect or too low.
Requests To Update the Cost of the Eddy Current Inspection
    Doug Morrow and two other commenters noted that the FAA's estimated 
labor rate is too low. Thomas Downey, Mitchell Ross, and twenty other 
commenters stated that the estimated cost of the proposed inspection, 
particularly the labor rate for an inspector qualified for eddy 
current, was underestimated. Piper submitted a list of estimated costs 
to conduct the eddy current inspection and to do any rework; nine other 
commenters agreed with Piper's costs. EAA, GAMA, Steven Ells, Doug 
Morrow, Piper, and two other commenters requested the estimated number 
of work-hours for the inspection be increased.
    The FAA agrees to revise the estimated cost of conducting the eddy 
current inspection. The labor rate of $85 per hour is provided by the 
FAA Office of Aviation Policy and Plans for use when estimating the 
labor costs for complying with AD requirements. However, the FAA 
acknowledges the higher hourly rate associated with the specialized 
skills that would be required by the proposed AD. The FAA has increased 
the cost estimate for the eddy current inspection to $600 in this 
SNPRM.
    The FAA observed several airplane inspections by private entities 
and the NTSB investigative team, which included representatives from 
NTSB, FAA, Piper, and Embry-Riddle. It took from 2 to 4 work-hours, 
inclusive of gaining access and restoring the airplane, to do the 
proposed inspections. However, in the NPRM the FAA did not take into 
account that a portion of the labor requires a second person (bolt 
removal and reinstallation). The FAA has revised the number of work-
hours estimated to do the inspections from 3 to 5 hours.
Requests To Update the Replacement Cost
    Thomas Rae, Doug Morrow, AOPA and six other commenters raised 
concerns about the cost to replace a spar or requested the FAA 
significantly increase the cost/number of hours to replace a wing spar. 
Two commenters noted that replacing a spar is not possible because 
there are no parts available, and three commenters questioned why a 
replacement spar must be a new spar. Piper recommended the FAA's 
estimated costs include the cost of replacing the entire wing.
    The FAA agrees with the comments concerning the number of labor 
hours and has increased the number of work-hours estimated for the 
wing-spar replacement from 32 to 80 hours. The FAA disagrees with 
adding the cost for wing replacement. The cost estimate in AD 
rulemaking actions include only the costs associated with complying 
with the AD. Although the FAA agrees that replacing the wing is an 
acceptable method of complying with a required spar replacement, that 
method is optional and not required by the AD. Although the FAA 
acknowledges the difficulty for some operators due to an unavailability 
of parts, this does not negate the need to correct the identified 
unsafe condition. The wing spar is critical for safe flight.
Requests To Include Indirect Costs
    Four individual commenters noted that the FAA's cost estimate does 
not include labor hours sufficient for indirect costs, such as 
painting, crating and transportation, and the diminished value of the 
aircraft.
    The FAA acknowledges the concerns raised by these commenters. 
However, the cost analysis in AD rulemaking actions typically includes 
only the costs of actions actually required by the rule. Cost estimates 
for ADs do not include indirect costs such as hours necessary for 
closing actions, costs for transportation to or from facilities for 
maintenance, or other losses. The FAA did not make changes to this 
SNPRM based on these comments.
Request To Revise the Cost for the Records Review
    AOPA requested the FAA revise the number of hours estimated to 
review the maintenance records and calculate the number of factored 
service hours. In support of its request, AOPA noted that the age of 
affected aircraft may be several decades old, necessitating more than 
the estimated two hours.
    The FAA agrees. Most general aviation airplane maintenance record 
entries are comprised of periodic inspections, which often include 
annual maintenance items, thus making such a review fairly 
straightforward. Flight schools and fleet operators often maintain 
electronic records, making data retrieval a simple matter. The FAA 
acknowledges that variations in record keeping styles encountered in 
older maintenance records may require additional time to review. 
Additionally, since the initial airplane maintenance records review to 
determine factored service hours effectivity is not considered a 
maintenance item, it can be accomplished by the owner/operator 
(certified pilot). The FAA has revised the number of hours to review 
the records from two hours to three hours and added language to clarify 
that an owner/operator may review the airplane maintenance records in 
this SNPRM.
Request To Increase the Number of Affected Airplanes in the Cost of 
Compliance Section
    Piper requested that the estimated costs be revised to include all 
affected airplanes worldwide instead of the 19,696 U.S.-registered 
airplanes identified in the NPRM. Piper further objected to the lack of 
an estimated fleet cost for the eddy current inspections, and stated 
40,856 airplanes should be included in the cost estimate because all 
airplanes over 10 years of age would be potentially subject to the 
inspections.
    The FAA disagrees. The cost analyses in AD rulemaking actions 
estimate the cost impact on U.S. operators. The FAA bases its estimate 
on the number of affected airplanes on the U.S. registry. Including all 
airplanes worldwide, as the commenter requested, would not

[[Page 34129]]

result in an estimate relevant to the cost impact of the proposed AD on 
U.S. operators.
    The FAA also disagrees that all 19,696 airplanes would be required 
to calculate the factored service hours. A small sampling of 
approximately 200 affected airplanes, aged 15 years and older, 
indicated that only 34 percent had reached the 5,000 hours TIS that 
would put them into the applicability of paragraph (c)(1) of the NPRM 
and require further calculation of the factored service hours. 
Therefore, the FAA estimates that a large number of the affected 
airplanes will not have reached 5,000 hours TIS, have missing logbooks, 
or have undergone a wing replacement and will therefore be able to 
defer further review of airplane maintenance records. The FAA did not 
makes changes to this SNPRM based on this comment.

L. Comment Regarding Effect of the Proposed AD on Intrastate Aviation 
in Alaska

    Piper requested the FAA correct the statement in the NPRM that the 
proposed AD would have no effect on intrastate commerce in Alaska. 
Piper stated that the proposed AD would affect 189 U.S. registered PA-
32-260 and PA-32-300 aircraft, which are widely utilized by many part 
135 operators who serve the Alaska communities that rely on aviation as 
their only mode of transportation.
    The FAA agrees and added clarifying language that the AD does 
affect operators in Alaska; however, it does not have a significant 
enough effect to make a regulatory distinction.

M. Comments Requesting an Extension of the Comment Period

    AOPA, EAA, GAMA, Piper, and seven individual commenters requested 
the FAA extend the comment period (from 45 days to 90 days) to allow 
additional time to comment because the NPRM was released preceding a 
holiday and subsequent government shutdown. Also, these commenters 
stated that additional time is needed for industry groups and the type 
certificate holder to evaluate the impact of the NPRM and to develop a 
solution.
    The FAA partially agrees. At the time the FAA issued the NPRM, an 
extension of the comment period was not necessary. During the partial 
government shutdown of December 22, 2018, through January 25, 2019, the 
online AD Docket at www.regulations.gov remained open and accepted 
public comments on the NPRM. In spite of the proximity to the holidays, 
over 170 separate submittals to the docket were received. However, 
since the FAA has revised the proposed AD actions and added airplanes 
to the Applicability, this SNPRM is reopening the comment period to 
provide the public an opportunity to comment on these proposed changes.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Piper Aircraft, Inc. Service Bulletin No. 1345, 
dated March 27, 2020 (Piper SB No. 1345). This service bulletin 
contains procedures for doing an eddy current inspection and 
instructions to report the results of the inspection to Piper and to 
replace the wing, wing spar, or spar section as necessary. 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.

Other Related Service Information

    The FAA reviewed Piper SB 886 and Piper SB 978A. These service 
bulletins contain procedures for determining initial and repetitive 
inspection times based on the aircraft's usage and visually inspecting 
the wing lower spar caps and the upper wing skin adjacent to the 
fuselage and forward of each main spar for cracks. The FAA also 
reviewed Piper Aircraft, Inc. Service Letter No. 997, dated May 14, 
1987, which contains procedures for replacing airplane wings.

FAA's Determination

    The FAA is proposing this AD because it evaluated all the relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design. 
Certain changes described above expand the scope of the NPRM. As a 
result, the FAA has determined that it is necessary to reopen the 
comment period to provide additional opportunity for the public to 
comment on this SNPRM.

Proposed Requirements of This SNPRM

    This SNPRM would require reviewing the airplane maintenance records 
to determine the number of 100-hour inspections completed on each 
installed main wing spar and using the number of 100-hour inspections 
to calculate the factored service hours for each main wing spar. This 
SNPRM would also require inspecting the two lower outboard main wing 
spar bolt holes on each wing for cracks once a main wing spar exceeds 
the specified factored service hours and replacing any main wing spar 
when a crack is indicated. This SNPRM would only apply when an airplane 
has either accumulated 5,000 or more hours TIS; has had either main 
wing spar replaced with a serviceable main wing spar (more than zero 
hours TIS); or has missing and/or incomplete maintenance records.
    This SNPRM specifies that the owner/operator (pilot) may do the 
aircraft maintenance records review and the factored service hours 
calculation. Reviewing maintenance records is not considered a 
maintenance action and may be done by a pilot holding at least a 
private pilot certificate. This action must be recorded in the aircraft 
maintenance records to show compliance with that specific action 
required by the AD.

Differences Between This SNPRM and the Service Information

    Piper SB 1345 specifies doing the eddy current inspection upon 
reaching 5,000 hours TIS; however, this SNPRM proposes using the 
factored service hours to identify the airplanes at the highest risk of 
developing fatigue cracks. Piper SB No. 1345 also specifies using its 
feedback form to report the eddy current inspection results, but this 
SNPRM proposes the use of a different form attached as appendix 1. In 
addition, this SNPRM requires replacement of the wing spar with a new 
(zero hours TIS) wing spar if cracks are found; however, Piper SB No. 
1345 allows replacement with parts that have been previously installed 
on an airplane.

Interim Action

    The FAA considers this SNPRM interim action. The inspection reports 
will provide the FAA additional data for determining the number of 
cracks present in the fleet. After analyzing the data, the FAA may take 
further rulemaking action.

Costs of Compliance

    The FAA estimates that this SNPRM affects 5,440 airplanes on U.S. 
registry. There are 10,881 airplanes of U.S. registry with a model and 
serial number shown in table 1 to paragraph (c) of the proposed AD. 
Based on a sample survey, the FAA estimates that 50 percent of those 
U.S.-registered airplanes will have reached the qualifying 5,000 hour 
TIS necessary to do the required logbook review.
    The FAA estimates the following costs to comply with this SNPRM:

[[Page 34130]]

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
              Action                      Labor cost             Parts cost           product        operators
----------------------------------------------------------------------------------------------------------------
Review airplane maintenance         3 work-hours x $85     Not applicable.......            $255      $1,387,200
 records and calculate factored      per hour = $255.
 service hours.
----------------------------------------------------------------------------------------------------------------

    The FAA estimates the following costs to do the eddy current 
inspection. Because some airplanes are only used non-commercially and 
will not accumulate the specified factored service hours in the life of 
the airplane, the FAA has no way of determining the number of airplanes 
that might need this inspection:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                   Action                                 Labor cost                Parts cost        product
----------------------------------------------------------------------------------------------------------------
Gain access to the left-hand (LH) and right- 2 work-hours x $85 per hour = $170.             $20            $190
 hand (RH) inspection areas.
Do eddy current inspections of the LH and    1 work-hour contracted service x                N/A             600
 RH lower main wing spar.                     $600 = $600.
Restore aircraft...........................  2 work-hours x $85 per hour = $170.             N/A             170
Report inspection results to...............  1 work-hour x $85 = $85............             N/A              85
the FAA and Piper Aircraft, Inc............
----------------------------------------------------------------------------------------------------------------

    The FAA estimates the following costs to do any necessary 
replacements that would be required based on the results of the 
proposed inspection. The FAA has no way of determining the number of 
aircraft that might need this replacement:

                                         On-Condition Replacement Costs
----------------------------------------------------------------------------------------------------------------
              Action                      Labor cost           Parts cost              Cost per product
----------------------------------------------------------------------------------------------------------------
Replace main wing spar...........  80 work-hours x $85 per           $5,540  $12,340 per wing spar.
                                    hour = $6,800 per wing
                                    spar.
----------------------------------------------------------------------------------------------------------------

Paperwork Reduction Act

    A federal agency may not conduct or sponsor, and a person is not 
required to respond to, nor shall a person be subject to a penalty for 
failure to comply with a collection of information subject to the 
requirements of the Paperwork Reduction Act unless that collection of 
information displays a currently valid OMB Control Number. The OMB 
Control Number for this information collection is 2120-0056. Public 
reporting for this collection of information is estimated to be 
approximately 1 hour per response, including the time for reviewing 
instructions, searching existing data sources, gathering and 
maintaining the data needed, completing and reviewing the collection of 
information. All responses to this collection of information are 
mandatory. Send comments regarding this burden estimate or any other 
aspect of this collection of information, including suggestions for 
reducing this burden to: Information Collection Clearance Officer, 
Federal Aviation Administration, 10101 Hillwood Parkway, Fort Worth, TX 
76177-1524.

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.
    The FAA is 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

    The FAA determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect on the States, on the relationship 
between the national Government and the States, or on the distribution 
of power and responsibilities among the various levels of government.
    For the reasons discussed above, I certify this proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Will not affect intrastate aviation in Alaska to the extent 
that it justifies making a regulatory distinction, 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.

List of Subjects in 14 CFR Part 39

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

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

[[Page 34131]]

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 adding the following new airworthiness 
directive (AD):

Piper Aircraft, Inc.: Docket No. FAA-2018-1046; Product Identifier 
2018-CE-049-AD.

(a) Comments Due Date

    The FAA must receive comments by July 20, 2020.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Piper Aircraft, Inc. (Piper) airplanes, 
certificated in any category, with a model and serial number shown 
in table 1 to paragraph (c) of this AD, and that meet at least one 
of the criteria in paragraphs (c)(1), (2), or (3) of this AD.

    Note 1 to paragraph (c) of this AD: An owner/operator with at 
least a private pilot certificate may do the aircraft maintenance 
records review to determine the applicability as specified in 
paragraph (c) of this AD.

    (1) Has accumulated 5,000 or more hours time-in-service (TIS); 
or
    (2) Has had either main wing spar replaced with a serviceable 
main wing spar (more than zero hours TIS); or
    (3) Has missing and/or incomplete maintenance records.
    [GRAPHIC] [TIFF OMITTED] TP03JN20.001
    
(d) Subject

    Joint Aircraft System Component (JASC)/Air Transport Association 
(ATA) of America Code 57, Wings.

(e) Unsafe Condition

    This AD was prompted by a report of a wing separation caused by 
fatigue cracking in a visually inaccessible area of the main wing 
lower spar cap. The FAA is issuing this AD to detect and correct 
fatigue cracks in the lower main wing spar cap bolt holes. The 
unsafe condition, if not addressed, could result in the wing 
separating from the fuselage in flight.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Definitions

    (1) ``TIS'' has the same meaning as the definition of ``time in 
service'' in 14 CFR 1.1.

[[Page 34132]]

    (2) For purposes of this AD, ``factored service hours'' refers 
to the calculated quantity of hours using the formula in paragraph 
(h)(2) of this AD, which accounts for the usage history of the 
airplane.

(h) Review Airplane Maintenance Records and Calculate Factored Service 
Hours for Each Main Wing Spar

    (1) Within 30 days after the effective date of this AD, review 
the airplane maintenance records and determine the number of 100-
hour inspections completed on the airplane since new and any record 
of wing spar replacement(s).
    (i) For purposes of this review, count any inspection conducted 
to comply with the 100-hour requirement of 14 CFR 91.409(b) 
pertaining to carrying persons for hire, such as in-flight training 
environments, even if the inspection was entered in the maintenance 
records as an ``annual'' inspection or as an ``annual/100-hour'' 
inspection. If the purpose of an inspection was to comply with Sec.  
91.409(b), then it must be counted. To determine the purpose of an 
inspection, note the repeating intervals between inspections, i.e., 
less than 10 months between, and typically 90-110 flight hours. An 
inspection entered as a ``100-hour'' inspection but done solely for 
the purpose of meeting the requirement to complete an annual 
inspection, or those otherwise not required by Sec.  91.409(b), need 
not be counted. For operators utilizing a progressive inspection 
program, count the completion of each Sec.  91.409(b) 100-hour 
interval as one inspection.
    (ii) If a main wing spar has been replaced with a new (zero 
hours TIS) main wing spar, count the number of 100-hour inspections 
from the time of installation of the new main wing spar.
    (iii) If a main wing spar has been replaced with a serviceable 
main wing spar (more than zero hours TIS) or the airplane 
maintenance records are missing or incomplete, the wing history 
cannot be determined. Perform the eddy current inspection as 
specified in paragraph (i) of this AD.
    (iv) The actions required by paragraph (h)(1) of this AD may be 
performed by the owner/operator (pilot) holding at least a private 
pilot certificate and must be entered into the aircraft records 
showing compliance with this AD in accordance with 14 CFR 43.9(a)(1) 
through (4), and 14 CFR 91.417(a)(2)(v). The record must be 
maintained as required by 14 CFR 91.417, 121.380, or 135.439.
    (2) Before further flight after completing the action in 
paragraph (h)(1) of this AD, calculate the factored service hours 
for each main wing spar using the formula in figure 1 to paragraph 
(h)(2) of this AD. Thereafter, after each annual inspection and 100-
hour inspection, recalculate/update the factored service hours for 
each main wing spar until the main wing spar has accumulated 5,000 
or more factored service hours.
[GRAPHIC] [TIFF OMITTED] TP03JN20.002

    (3) An example of determining factored service hours for an 
airplane with no 100-hour inspections is as follows: The airplane 
maintenance records show that the airplane has a total of 12,100 
hours TIS, and only annual inspections have been done. None of the 
annual inspections were done for purposes of compliance with Sec.  
91.409(b). Both main wing spars are original factory installed. In 
this case, N = 0 and T = 12,100. Use those values in the formula as 
shown in figure 2 to paragraph (h)(3) of this AD.
[GRAPHIC] [TIFF OMITTED] TP03JN20.003

[[Page 34133]]

    (4) An example of determining factored service hours for an 
airplane with both 100-hour and annual inspections is as follows: 
The airplane was originally flown for personal use, then for 
training for a period of time, then returned to personal use. The 
airplane maintenance records show that the airplane has a total of 
5,600 hours TIS, and nineteen 100-hour inspections for purposes of 
compliance with Sec.  91.409(b) have been done. Both main wing spars 
are original factory installed. In this case, N = 19 and T = 5,600. 
Use those values in the formula shown in figure 3 to paragraph 
(h)(4) of this AD. First, calculate commercial use time by 
multiplying (N x 100). Next, subtract that time from the total time, 
and divide that quantity by 17. Add the two quantities to determine 
total factored service hours.
[GRAPHIC] [TIFF OMITTED] TP03JN20.004

(i) Eddy Current Inspect

    Within the compliance time specified in either paragraph (i)(1) 
or (2) of this AD, as applicable, eddy current inspect the inner 
surface of the two lower outboard bolt holes on the lower main wing 
spar cap for cracks using steps 1 through 3 in the Instructions of 
Piper Aircraft, Inc. Service Bulletin No. 1345, dated March 27, 
2020. Although Piper SB No. 1345 specifies NAS 410 Level II or Level 
III certification to perform the inspection, this AD allows Level II 
or Level III qualification standards for inspection personnel using 
any inspector criteria approved by the FAA.

    Note 2 to paragraph (i) of this AD:  Adivsory Circular 65-31B 
contains FAA-approved Level II and Level III qualification standards 
criteria for inspection personnel doing nondestructive test (NDT) 
inspections.

    (1) Within 100 hours TIS after complying with paragraph (h) of 
this AD or within 100 hours TIS after a main wing spar accumulates 
5,000 factored service hours, whichever occurs later; or
    (2) For airplanes with an unknown number of factored service 
hours on a main wing spar, within the next 100 hours TIS after the 
effective date of this AD or within 60 days after the effective date 
of this AD, whichever occurs later.

(j) Replace the Main Wing Spar

    If a crack is found during an inspection required by paragraph 
(i) of this AD, before further flight, replace the main wing spar 
with a new (zero hours TIS) main wing spar.

(k) Install New Bolts

    Before further flight after completing the actions required by 
paragraph (i) or (j) of this AD, install new bolts by following step 
6 of Piper Aircraft, Inc. Service Bulletin No. 1345, dated March 27, 
2020.

(l) Report Inspection Results

    Within 30 days after completing an inspection required by 
paragraph (i) of this AD, using Appendix 1, ``Inspection Results 
Form,'' of this AD, report the inspection results to the FAA at the 
Atlanta ACO Branch and to Piper. Submit the report to the FAA and 
Piper using the contact information found on the form in appendix 1 
of this AD.

(m) Special Flight Permit

    A special flight permit may only be issued to operate the 
airplane to a location where the inspection requirement of paragraph 
(i) of this AD can be performed. This AD prohibits a special flight 
permit if the inspection reveals a crack in a main wing spar.

(n) Paperwork Reduction Act Burden Statement

    A federal agency may not conduct or sponsor, and a person is not 
required to respond to, nor shall a person be subject to a penalty 
for failure to comply with a collection of information subject to 
the requirements of the Paperwork Reduction Act unless that 
collection of information displays a currently valid OMB Control 
Number. The OMB Control Number for this information collection is 
2120-0056. Public reporting for this collection of information is 
estimated to be approximately 1 hour per response, including the 
time for reviewing instructions, searching existing data sources, 
gathering and maintaining the data needed, completing and reviewing 
the collection of information. All responses to this collection of 
information are mandatory. Send comments regarding this burden 
estimate or any other aspect of this collection of information, 
including suggestions for reducing this burden to: Information 
Collection Clearance Officer, Federal Aviation Administration, 10101 
Hillwood Parkway, Fort Worth, TX 76177-1524.

(o) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Atlanta ACO Branch, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request 
to your principal inspector or local Flight Standards District 
Office, as appropriate. If sending information directly to the 
manager of the certification office, send it to the attention of the 
person identified in paragraph (p) of this AD.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(p) Related Information

    (1) For more information about this AD, contact Dan McCully, 
Aerospace Engineer, Atlanta ACO Branch, FAA, 1701 Columbia Avenue, 
College Park, Georgia 30337; phone:

[[Page 34134]]

(404) 474-5548; fax: (404) 474-5605; email: william.mccully@faa.gov.
    (2) For service information identified in this AD, Piper 
Aircraft, Inc., 2926 Piper Drive, Vero Beach, Florida 32960; 
telephone: (772) 567-4361; internet: www.piper.com. You may view 
this service information at the FAA, Airworthiness Products Section, 
Operational Safety Branch, 901 Locust, Kansas City, Missouri 64106. 
For information on the availability of this material at the FAA, 
call (816) 329-4148.
BILLING CODE 4910-13-P

[[Page 34135]]

[GRAPHIC] [TIFF OMITTED] TP03JN20.005

[[Page 34136]]

    Issued on May 8, 2020.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.

[FR Doc. 2020-11343 Filed 6-2-20; 8:45 am]
 BILLING CODE 4910-13-C