Federal Register / Vol. 77, No. 180 / Monday, September 17, 2012 / Rules and Regulations 56993 

(3) If any damage or leakage is found as a 

result of any inspection required in 

paragraph (f)(2) of this AD, before further 

flight, do the applicable corrective actions 

following the instructions in Costruzioni 

Aeronautiche TECNAM P2006T Aircraft 

Maintenance Manual, Document No. 2006/ 

045, 2nd Edition—Revision 1, dated April 27, 

2011. 

(g) Other FAA AD Provisions 

The following provisions also apply to this 

AD: 

(1) Alternative Methods of Compliance 

(AMOCs): The Manager, Standards Office, 

FAA, has the authority to approve AMOCs 

for this AD, if requested using the procedures 

found in 14 CFR 39.19. Send information to 

ATTN: Albert Mercado, Aerospace Engineer, 

FAA, Small Airplane Directorate, 901 Locust, 

Room 301, Kansas City, Missouri 64106; 

telephone: (816) 329–4119; fax: (816) 329– 

4090; email: albert.mercado@faa.gov. Before 

using any approved AMOC on any airplane 

to which the AMOC applies, notify your 

appropriate principal inspector (PI) in the 

FAA Flight Standards District Office (FSDO), 

or lacking a PI, your local FSDO. 

(2) Airworthy Product: For any requirement 

in this AD to obtain corrective actions from 

a manufacturer or other source, use these 

actions if they are FAA-approved. Corrective 

actions are considered FAA-approved if they 

are approved by the State of Design Authority 

(or their delegated agent). You are required 

to assure the product is airworthy before it 

is returned to service. 

(3) Reporting Requirements: For any 

reporting requirement in this AD, 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 current 

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 5 minutes per response, 

including the time for reviewing instructions, 

completing and reviewing the collection of 

information. All responses to this collection 

of information are mandatory. Comments 

concerning the accuracy of this burden and 

suggestions for reducing the burden should 

be directed to the FAA at: 800 Independence 

Ave. SW., Washington, DC 20591, Attn: 

Information Collection Clearance Officer, 

AES–200. 

(h) Related Information 

Refer to MCAI European Aviation Safety 

Agency (EASA) AD No.: 2012–0043, dated 

March 19, 2012; Costruzioni Aeronautiche 

Tecnam Service Bulletin SB 80–CS, dated 

January 2, 2012; and Costruzioni 

Aeronautiche Tecnam P2006T Maintenance 

Manual, 2nd Edition, Revision 1, dated April 

7, 2011, for related information. For service 

information related to this AD, contact 

Costruzioni Aeronautiche TECNAM 

Airworthiness Office, Via Maiorise—81043 

Capua (CE) Italy; telephone: +39 0823 

620134; fax: +39 0823 622899; email: 

m.oliva@tecnam.com, or 

g.paduano@tecnam.com; Internet: 

www.tecnam.com. You may review copies of 

the 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. 

(i) Material Incorporated by Reference 

(1) The Director of the Federal Register 

approved the incorporation by reference 

(IBR) of the service information listed in this 

paragraph under 5 U.S.C. 552(a) and 1 CFR 

part 51. 

(2) You must use this service information 

as applicable to do the actions required by 

this AD, unless the AD specifies otherwise. 

(i) Costruzioni Aeronautiche TECNAM 

Service Bulletin SB 80–CS, dated January 2, 

2012; and 

(ii) Costruzioni Aeronautiche TECNAM 

P2006T Aircraft Maintenance Manual, 

Document No. 2006/045, 2nd Edition— 

Revision 1, dated April 27, 2011. 

(3) For Costruzioni Aeronautiche TECNAM 

service information identified in this AD, 

contact Costruzioni Aeronautiche TECNAM 

Airworthiness Office, Via Maiorise—81043 

Capua (CE) Italy; telephone: +39 0823 

620134; fax: +39 0823 622899; email: 

m.oliva@tecnam.com, or 

g.paduano@tecnam.com; Internet: 

www.tecnam.com. 

(4) You may review copies of the 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. 

(5) You may view this service information 

that is incorporated by reference at the 

National Archives and Records 

Administration (NARA). For information on 

the availability of this material at NARA, call 

202–741–6030, or go to: http:// 

www.archives.gov/federal-register/cfr/ibrlocations.html. 

Issued in Kansas City, Missouri, on August 

29, 2012. 

Earl Lawrence, 

Manager, Small Airplane Directorate, Aircraft 

Certification Service. 

[FR Doc. 2012–21927 Filed 9–14–12; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2011–0639; Directorate 

Identifier 2011–CE–016–AD; Amendment 

39–17169; AD 2012–17–06] 

RIN 2120–AA64 

Airworthiness Directives; Piper 

Aircraft, Inc. Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: We are adopting a new 

airworthiness directive (AD) for certain 

Piper Aircraft, Inc. Models PA–24, PA– 

24–250, and PA–24–260 airplanes. This 

AD was prompted by reports of cracks 

developing in the stabilator horn 

assembly. This AD requires replacement 

of the stabilator horn assembly and/or 

repetitive inspections of the stabilator 

horn assembly for corrosion or cracks, 

as applicable. Corrosion or cracks could 

lead to failure of the stabilator horn. 

Consequently, failure of the stabilator 

horn could lead to a loss of pitch control 

in flight. We are issuing this AD to 

correct the unsafe condition on these 

products. 

DATES: This AD is effective October 22, 

2012. 

The Director of the Federal Register 

approved the incorporation by reference 

of a certain publication listed in the AD 

as of October 22, 2012. 

ADDRESSES: For service information 

identified in this AD, contact Piper 

Aircraft, Inc., 2926 Piper Drive, Vero 

Beach, Florida 32960; telephone: (772) 

567–4361; fax: (772) 978–6573; Internet: 

http://www.newpiper.com/company/ 

publications.asp. You may review 

copies of the referenced service 

information at the FAA, Small Airplane 

Directorate, 901 Locust St., 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 http:// 

www.regulations.gov; 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 K. 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 to include an AD that would 

apply to the specified products. That 


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56994 Federal Register / Vol. 77, No. 180 / Monday, September 17, 2012 / Rules and Regulations 

NPRM published in the Federal 

Register on June 22, 2011 (76 FR 36395). 

That NPRM proposed to require 

replacement of the stabilator horn 

assembly and/or repetitive inspections 

of the stabilator horn assembly for 

corrosion or cracks, as applicable. 

Comments 

We gave the public the opportunity to 

participate in developing this AD. The 

following presents the comments 

received on the proposal and the FAA’s 

response to each comment. 

Support for the Proposed Initial 

Inspection 

Comments from Kristin Amelia 

Winter, Charles Parker, Carl Schoolcraft, 

Dave Fitzgerald for the International 

Comanche Society (ICS), Hans Neubert 

for the ICS, Brian Kotso, and John F. 

Murray were supportive of the AD’s 

requirement for an initial inspection. 

We did not change this final rule AD 

action based on these comments. 

Request FAA To Withdraw NPRM (76 

FR 36395, June 22, 2011) Due to 

Adequacy of External Inspections 

Phil Ciholas requested we reconsider 

the NPRM (76 FR 36395, June 22, 2011) 

requirements and noted that even the 

most severe horn cracking reported 

(propagated through the part to an 

exterior surface and was visually 

detectable without disassembly) had not 

resulted in complete horn failure or the 

severity of loss of control postulated in 

the justification for the AD. The 

commenter stated that no loss of control 

incidents or accidents have ever been 

documented that can be attributed to 

this failure mode. Given the statistical 

distribution of cracks reported, the 

ability of existing external inspections 

to detect cracks prior to complete failure 

of the horn, and the lack of any actual 

complete failures; the commenter felt 

the internal inspection requiring 

disassembly is unwarranted on most 

aircraft, especially recent serial number 

aircraft, unless there is other evidence of 

potential issues observed on a particular 

aircraft. We infer the commenter 

requested to withdraw the current 

proposal. 

We disagree with the request to 

withdraw the NPRM (76 FR 36395, June 

22, 2011). A cracked stabilator horn 

coupled with the aircraft flight envelope 

conditions could create an unsafe 

scenario even though there has not been 

an in-flight event. A cracked stabilator 

horn reduces the aircraft’s structural 

load limits. 

We did not change this final rule AD 

action based on these comments. 

Request To Clarify Applicability 

(Affected Part Numbers (P/Ns) and 

Configurations) 

David Ray Fitzgerald, Robert (no last 

name given), Patrick D. Donovan, 

Edward P. Horan, Steven Fischer, Phil 

Ciholas, Dave Fitzgerald for ICS, Daniel 

Jacob Katz, Arthur John Beyer, Hans 

Neubert for the ICS, Brian Kotso, John 

F. Murray, and Dennis Boykin requested 

we clarify the applicability to clearly 

state the affected horn P/Ns and clarify 

whether other current and future horns 

(supplemental type certificates (STC), 

and so forth) are/will be affected. The 

commenters noted that the text of the 

proposed AD did not clearly state the 

affected part numbers. 

Robert (no last name given), Steven 

Fischer, Daniel Jacob Katz, Hans 

Neubert for ICS, and John F. Murray 

also requested we address the 

configuration of Models PA–24, PA–24– 

250, and PA–24–260 airplanes using the 

same horn but installed with thicker 

torque tubes used on the Models PA– 

24–400, PA–30, and PA–39 airplanes as 

the proposed AD did not currently make 

mention of this configuration. They 

requested we consider excluding the 

airplanes configured with the thicker 

torque tubes from the applicability or 

including them as terminating action. 

Phil Ciholas, Arthur John Beyer, and 

Dennis Boykin requested we address 

potential material and process changes 

during production of the Models PA–24, 

PA–24–250, and PA–24–260 airplanes, 

amending the NPRM (76 FR 36395, June 

22, 2011) to apply to only those aircraft 

that have experienced issues. 

Dennis Boykin noted that the 

manufacturing cycle between the 

original castings (about 1957) and the 

final production in 1972 of the Model 

PA–24–260 airplane precluded the 

requirement to ensure that similar 

castings, raw materials, and processes 

were in place, not just a similar design. 

Dennis Boykin was not aware of any 

Model PA–24–260 airplane’s stabilator 

horn that has been separated, inspected, 

and found deficient. 

We partially agree with the 

commenters. We agree with clarifying 

the affected P/Ns because the issue is 

specific to the combination of the P/N 

and models in the original NPRM (76 FR 

36395, June 22, 2011). However, we 

disagree with excluding aircraft with the 

thicker torque tube installed or making 

the installation of the thicker torque 

tube a terminating action. No 

documentation has been supplied to 

provide approval for the installation of 

thicker torque tubes on the Models PA– 

24, PA–24–250, or PA–24–260 

airplanes, and the torque tube is not the 

only contributing factor to the unsafe 

condition. The FAA has determined the 

condition is likely to exist or develop in 

other products of the same type design. 

We have insufficient data to show that 

airplanes modified with the thicker 

torque tube do not have the unsafe 

condition. 

We also disagree with excluding 

stabilator horns manufactured later in 

the production cycle. We have no record 

of castings, raw materials, and/or 

processes changing significantly enough 

to provide justification to exclude those 

airplanes from this AD action. 

If an owner/operator submits 

substantiating data to support the 

installation of the thicker torque tube as 

an alternative method of compliance 

(AMOC) to this requirement, the FAA 

will review and consider all AMOC 

requests we receive provided they 

follow the procedures in 14 CFR 39.19 

and this AD. 

We changed the AD’s applicability in 

this final rule AD action to include the 

horn P/N. 

Request To Lower Torque Value for 

Horn Installation 

Lawrence La Beau, Charles Parker, 

Eric Paul, Tom Veatch, Ivan R. Wilson, 

Patrick D. Donovan, Ken E. Shaffer, 

Patric Barry, John Trudel, Carl 

Schoolcraft, Phil Ciholas, Dave 

Fitzgerald for the ICS, Andrew Detsch, 

Hans Neubert for the ICS, Brian Kotso, 

John F. Murray, and Allan H. Bieck 

requested that the AD state an 

appropriate lower shear nut torque 

value for the bolts common to the 

stabilator horn and torque tube. Phil 

Ciholas requested we add horn 

deformation limits as a way to control 

the installation torque and related stress 

corrosion cracking. Charles Parker, Eric 

Paul, Tom Veatch, Ivan R. Wilson, 

Patric Barry, John Trudel, Dave 

Fitzgerald for the ICS, Hans Neubert for 

the ICS, and Brian Kotso requested we 

consider an initial inspection and 

reinstallation with the lower torque 

value as terminating action for the AD. 

Eric Paul and John F. Murray requested 

we lower the torque value of the stop 

collar bolts. Phil Ciholas requested we 

consider switching to shear nuts when 

any work is done on the joint. 

The commenters stated over-torque is 

the root cause of the stress corrosion 

condition and the procedure does not 

clearly require a lower torque value. 

None of the commenters provided 

justification for the use of stop collar 

bolts separate from the horn bolts or for 

the shear nuts. 

We agree with adding the installation 

torque value for the bolts common to the 

horn and torque tube into the AD 


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Federal Register / Vol. 77, No. 180 / Monday, September 17, 2012 / Rules and Regulations 56995 

procedures because it is a factor in 

mitigating the unsafe condition. We will 

also coordinate with the airplane’s 

manufacturer on clarifying the airplane 

maintenance manual procedures for 

torque of these bolts. However, we 

disagree with adding an initial 

inspection and reinstallation of the 

torque tube with the lower torque value 

as terminating action for the AD. 

Although the torque value is a 

contributing factor, it is not the only 

factor (others are balance arm 

interference fit, basic material 

susceptibility, and corrosion potential). 

No sufficient correlation has been 

established between the torque value 

and deformation and subsequent stress 

corrosion cracking. Consequently, we 

disagree with adding horn deformation 

limits as a way to control the 

installation torque and related stress 

corrosion cracking. 

We disagree with mandating a lower 

torque value of the stop collar bolts or 

mandating a switch to shear nuts when 

any work is done on the joint. The stop 

collar bolts did not contribute to the 

unsafe condition, and we cannot 

mandate actions through an AD that are 

unnecessary to correct the unsafe 

condition. There is no current data for 

approval to change the configuration to 

shear nuts. 

We changed the AD by adding the 

installation torque value for the bolts 

common to the horn and torque tube 

into the AD procedures. 

Request To Use Thicker Torque Tube 

With Horn 

Lawrence La Beau, Randy Black, 

Anonymous, Donald Dummer, Albert 

Powers, Steven Fischer, Stewart 

Campbell, Miller Duffield Einsel, 

Robert, Eric Paul, Tom Veatch, Patric 

Barry, John Trudel, Edward P. Horan, 

Carl Schoolcraft, Steven Fischer, Phil 

Ciholas, Dave Fitzgerald for the ICS, 

Daniel Jacob Katz, Hans Neubert for the 

ICS, Lawrence E. Pride, Jim Ritter, Brian 

Kotso, and John F. Murray noted thicker 

torque tubes discovered during the ICS’ 

survey targeted inspections at the horn. 

This survey was beyond the current 

maintenance program. The commenters 

cited the thicker torque tube could 

lessen the potential for stress corrosion 

cracking due to horn deformation. 

Robert, Steven Fischer, Daniel Jacob 

Katz, Hans Neubert for ICS, and John F. 

Murray requested we address the 

configuration of Models PA–24, PA–24– 

250, and PA–24–260 airplanes with the 

subject horn but installed with thicker 

torque tubes. 

We do not agree with the commenters. 

We disagree with authorizing the 

installation of the thicker torque tube. 

No documentation has been supplied to 

provide approval for installation of the 

thicker torque tube configuration on any 

airplanes affected by this AD. 

The FAA will review and consider 

any AMOC to support the installation of 

the thicker tube provided it follows the 

procedures in 14 CFR 39.19 and this 

AD. 

We did not change this final rule AD 

action based on these comments. 

Request To Provide for a Terminating 

Action to the Repetitive Inspections 

Kristin Amelia Winter, Lawrence 

Zubel, Charles Parker, Randy Black, 

Donald Dummer, Steven Fischer, 

Stewart Campbell, Miller Duffield 

Einsel, Eric Paul, Tom Veatch, Ivan R. 

Wilson, Patric Barry, Steven Fischer, 

Phil Ciholas, Dave Fitzgerald for the 

ICS, Daniel Jacob Katz, Hans Neubert for 

the ICS, Jim Ritter, Brian Kotso, and 

John F. Murray requested a terminating 

action to the repetitive inspections. All 

the commenters proposed various 

actions (that is, use of lower installation 

torque value, installation of a thicker 

torque tube, installation of replacement 

horn by way of Australian Civil 

Aviation Safety Authority (CASA) 

CASA Supplemental Type Certificate 

(STC) SVA 532, and terminating action 

based on additional data collected 

during the inspections) with varying 

levels of supporting data. 

We disagree because no proposed 

terminating action eliminates all the 

contributing factors to the unsafe 

condition. The individual proposed 

actions have been addressed in other 

requested changes to the AD. The 

inspection or replacement programs will 

manage the issue to an acceptable level 

of risk. 

We will consider proposals for a 

terminating action as an AMOC 

provided the procedures of 14 CFR 

39.19 and this AD are followed. 

We did not change this final rule AD 

action based on these comments. 

Request To Credit for Previous 

Compliance 

Commenters David Charles Meigs, 

Randy Black, Steven Fischer, Hans 

Neubert for the ICS, and Brian Kotso 

noted that operators have typically been 

allowed credit for previous compliance 

in AD actions. All commenters 

requested provision for credit when 

compliance to the requirements has 

already been accomplished. 

We agree that credit should be given 

when compliance to the requirements 

has already been done. The AD already 

allows for such credit by stating ‘‘unless 

already done’’ in paragraph (f) of the 

AD. As long as the requirements of the 

AD are followed, credit is available. Any 

other actions taken would need to be 

submitted as an AMOC following 

paragraph (h) of the AD. 

We did not change this final rule AD 

action based on these comments. 

Request To Clarify the AD Applicability 

to Replacement Parts 

Commenters David Charles Meigs, 

Randy Black, Steven Fischer, Hans 

Neubert for the ICS, Brian Kotso stated 

that the AD applicability is not clearly 

defined in terms of both the susceptible 

horn part number and the affected 

models. Several commenters request 

clarification of the AD applicability to 

replacement parts, particularly the horn 

in CASA STC SVA 532. 

We partially agree with clarification 

on the applicability because the focus of 

this AD is the horn P/N as discussed in 

the previous issue ‘‘Request To Clarify 

Applicability.’’ We disagree with 

specifically addressing the CASA STC 

because the STC is still under review for 

FAA validation and not all design issues 

have been addressed at this point. Any 

action relating the STC to the AD will 

be documented during the FAA review 

of the CASA STC. 

As discussed previously, we changed 

the AD’s applicability to include the 

horn P/N. 

Request To Increase Initial Compliance 

Time 

Patric Barry and Phil Ciholas 

expressed concerns with the availability 

of parts and shop capacity. The 

commenters requested an increase in 

the initial compliance time. 

We disagree with the commenters. 

The unsafe condition must be addressed 

in a timely manner. The FAA will 

consider AMOCs following the 

procedures in 14 CFR 39.19 and this AD 

to address any potential parts 

availability or shop capacity issues. 

We did not change this final rule AD 

action based on these comments. 

Request To Change Units of Compliance 

Times 

Commenters Randy Black, Patrick D. 

Donovan, Carl Schoolcraft, Hans 

Neubert for the ICS, John F. Murray, and 

Allan H. Bieck requested changing 

compliance time criteria. Patrick D. 

Donovan, Hans Neubert for the ICS, and 

John F. Murray asked that only calendar 

time be used for compliance times. Carl 

Schoolcraft and Allan H. Bieck 

requested that only TIS be used for 

compliance times. The commenters 

noted that stress corrosion cracking 

(SCC) is a time-related function and not 

TIS. Carl Schoolcraft noted the calendar 

time limit to be arbitrary and to have no 


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bearing on the condition of the horn. 

Allan H. Bieck commented TIS is what 

puts strain on the horn, not idle 

calendar time while the aircraft sits in 

a hangar. 

We disagree with eliminating the 

calendar time compliance. Calendar 

time is a key factor in SCC. We also 

disagree with removing the operational 

time (TIS) requirement as corrosion in 

the torque tube is a contributing factor, 

and the established actions for the 

corrosion currently have both a calendar 

and TIS requirement. We will retain our 

compliance time using both calendar 

time and TIS. 

We did not change this final rule AD 

action based on these comments. 

Request To Eliminate the Repetitive 

Inspection Requirement 

Kristin Amelia Winter, Charles 

Parker, Albert Powers, Ken E. Shaffer, 

John Trudel, Dave Fitzgerald for the ICS, 

Phil Ciholas, and Brian Kotso requested 

eliminating the repetitive inspection 

requirement. Commenters justify 

eliminating the repetitive inspections by 

stating the cracks do not appear to be 

time or use related, there is low or no 

history of cracking in the fleet, there 

have been no catastrophic horns failures 

in service, and there is potential for 

terminating action. 

We do not agree because SCC is 

inherently time-related and indirectly 

driven by operational usage. Not all 

aircraft will crack, and those that do 

will not crack at the same time. SCC has 

several contributing factors that add to 

the variability. For instance, typical 

fatigue cracking includes scatter factors 

on the order of four to determine the 

appropriate intervals to take action. 

While high-time aircraft with no 

cracking is useful data, it does not 

eliminate the need for action. As for the 

volume of findings, the quantity 

compared to the entire fleet size is low. 

However, when measured against the 

quantity of valid inspections performed, 

the find rate is as high as 20 percent. 

It is also true that no parts have failed 

catastrophically in flight and the 

findings have been during the ICS’ 

survey targeted at the horn. Note that 

this survey was beyond the current 

required maintenance program. A 

cracked horn coupled with the aircraft 

flight envelope conditions could still 

create an unsafe scenario even though 

there has not been an in-flight event. In 

fact, the service history provides 

evidence of extensive cracking on both 

sides of the torque tube bore leading to 

the potential unsafe condition. As 

discussed in other responses to 

commenter requests, no proposed 

terminating action eliminates all the 

contributing factors to the unsafe 

condition. The inspection or 

replacement programs will manage the 

issue to an acceptable level of risk. 

We did not change this final rule AD 

action based on these comments. 

Request To Change Inspection Intervals 

Eric Paul, Ivan R. Wilson, Patrick D. 

Donovan, Patric Barry, Carl Schoolcraft, 

Phil Ciholas, Dave Fitzgerald for the 

ICS, Andrew Detsch, John F. Murray, 

and Allan H. Bieck requested an 

increased repetitive interval from 100 

hours to 200 hours, 500 hours, 1,000 

hours, or 2,000 hours. 

Patrick D. Donovan, Patric Barry, and 

Dave Fitzgerald for the ICS noted that 

taking half of the average discovery time 

(stated as 4,000 hours TIS) should be a 

reasonable approach to establish a 

repetitive interval. Ivan R. Wilson and 

Jim Ritter also referenced the long 

service history of the fleet 

(approximately 50 years and several 

thousand hours). Andrew Detsch 

asserted that the cracks occurred later in 

the service life or did not grow. Arthur 

John Beyer provided information that 

they inspected the component twice 

near 4,000 TIS at an interval of 4 years 

and 264 hours with no cracking 

observed at either inspection. Han 

Neubert recommended establishing 

intervals based on a study of 2014–T6 

behavior under stress corrosion to 

define stress and environment 

thresholds similar to a provided report 

about stress corrosion susceptibility, 

Time Exposure Studies on Stress 

Corrosion Cracking of Aluminum 2014– 

T6, 2219–T87, 2014–T651, 7075–T651, 

and Titanium 6Al–4V, dated June 1, 

1973 (http://ntrs.nasa.gov/archive/nasa/ 

casi.ntrs.nasa.gov/19730009798_

1973009798.pdf). Charles Parker, Arthur 

John Beyer, and Jim Ritter requested 

justification for the current intervals. 

We partially agree with adjusting the 

repetitive interval from 3 years to 5 

years because it would align with the 

rationale for the existing 10-year or 

1,000-hour interval and other guidance 

used to establish the intervals. There is 

no need to decrease the interval to 200 

hours as the AD provides an interval of 

500 hours. 

We disagree with increasing the 

repetitive interval beyond 500 hours for 

several reasons. We must consider many 

factors to define an appropriate 

inspection interval. 

The first factor, the design safety 

requirement, does not allow strength 

degradation below design ultimate value 

or stiffness degradation for flutter. 

Advisory Circular (AC) 23–13A, Fatigue, 

Fail-Safe, and Damage Tolerance 

Evaluation of Metallic Structure for 

Normal, Utility, Acrobatic, and 

Commuter Category Airplanes, dated 

September 29, 2005, (http://rgl.faa.gov/ 

Regulatory_and_Guidance_Library/

rgAdvisoryCircular.nsf/list/AC%2023-

13A/$FILE/ac23-13A.pdf) describes how 

ensuring no detectable cracks within the 

operational life of the aircraft through 

an appropriate inspection interval meets 

the design requirement. The existing 

findings of cracks do not meet these 

requirements. Simply, the aircraft is not 

certificated to meet airworthiness 

standards with a known crack. 

A ‘‘detectable’’ size for a crack is a 

value established for the specific 

inspection method in a specific 

application. The discovered cracks had 

far exceeded detectable size before they 

were found during the targeted 

inspections. This is due in part to no 

targeted inspections until discovery of 

corrosion issues on the attached torque 

tube several years ago. Following the 

approach in AC 23–13A, the estimated 

service history would provide a test life 

of approximately 4,000 hours, then 

apply a scatter factor of approximately 

4, yielding 1,000 hours. Again, this 

should be for detectable cracks that do 

not degrade the strength and stiffness. 

An additional factor of 2 (providing two 

inspection opportunities) could be 

applied to cover that portion, yielding 

an inspection at 500 hours. Note, this is 

only an example to show the 

reasonableness of the proposed interval 

based on service data. The interval is 

driven primarily by calendar time using 

a similar approach. 

The second factor is the probabilistic 

nature of cracking. While some hightime or aged aircraft do not exhibit 

cracking, we expect this in the 

distribution and is insufficient rationale 

to shorten the interval. For example, the 

data point of a 4-year/264-hour interval 

is useful, but many more data points 

would be necessary to support an 

increased interval. 

The third factor is associated with 

service history and the existing intervals 

for related issues on the stabilator 

control system. For the attached torque 

tube, Piper Aircraft, Inc. Service 

Bulletin No. 1160, dated December 26, 

2005, specifies a 10-year repetitive 

inspection for corrosion. Also for the 

tube, Special Airworthiness Information 

Bulletin CE–04–88, dated September 15, 

2004, (http://rgl.faa.gov/Regulatory_

and_Guidance_Library/rgSAIB.nsf/0/

77fc29bb15c8a85b8625721f0052ecb4/

$FILE/CE-04-88.pdf) specifies a 3-year 

or 500-hour repetitive inspection, and 

AD 74–13–03 (41 FR 17371, April 26, 

1976) requires a 3-year or 500-hour 

repetitive inspection. These issues are 


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corrosion-related and corrosion is a 

factor in the SCC of the horn. 

The assertion that cracks occurred 

later or early in service and then did not 

grow has no supporting data to use in 

establishing intervals. 

The FAA reviewed the report 

provided by Hans Neubert, Time 

Exposure Studies on Stress Corrosion 

Cracking of Aluminum 2014–T6, 2219– 

T87, 2014–T651, 7075–T651, and 

Titanium 6Al–4V, dated June 1, 1973, 

(http://ntrs.nasa.gov/archive/nasa/casi.

ntrs.nasa.gov/19730009798_

1973009798.pdf). While additional work 

could be coordinated if funding is 

available, we must first manage the 

known condition. The report already 

alludes to the fact that aluminum 2014– 

T6 is particularly susceptible to SCC 

which invalidates the assumption that 

aluminum 2014–T6 would have 

equivalent behavior to other test 

material. There is no true stress 

corrosion threshold (similar to a fatigue 

endurance limit) for aluminum 2014– 

T6. Additional work would be required 

to validate the stresses from all 

contributing factors once any type of 

threshold was tested. 

We changed the repetitive interval for 

inspected parts in paragraph (g)(1) of the 

AD from 3 years to 5 years. 

Request To Reconsider the Requirement 

for Repetitive Inspection of the 

Assembly 

Kristin Amelia Winter, Steven 

Fischer, George Edward White, Patric 

Barry, Carl Schoolcraft, Dave Fitzgerald 

for the ICS, Andrew Detsch, Arthur John 

Beyer, Jim Ritter, and John F. Murray 

requested we reconsider the 

requirement for repetitive, intrusive 

inspection of the assembly. The 

commenters were concerned that 

repetitive disassembly and re-assembly 

of the structure could introduce new 

risks from wear, assembly errors, etc. 

We disagree with the commenters. 

While we agree that there are potential 

risks with the repeated inspection, the 

current issue is a higher risk and we 

must address the known unsafe 

condition. The need for a repetitive 

inspection has been addressed 

elsewhere in this final rule AD action. 

Installation of the new parts would 

minimize the stated risk of repeated 

disassembly and reassembly and 

achieve the maximum interval of 10 

years or 1,000 hours. 

We did not change this final rule AD 

action based on these comments. 

Request To Allow Alternative 

Inspection Methods 

George Edward White, Patrick D. 

Donovan, Patric Barry, Phil Ciholas, and 

Dave Fitzgerald for the ICS requested 

allowance for alternative, less intrusive, 

inspection methods such as X-ray, 

magnetic particle inspection, or bolt 

torque and measured torque tube 

deformation. The commenters reasoned 

that the alternative inspection methods 

could avoid disassembly and 

reassembly. 

We do not agree with this request 

because: 

• X-ray does not provide a 

sufficiently high probability (reliability) 

of detection for cracks at sizes needed 

to control the unsafe condition. 

• Magnetic particle inspection is for 

magnetic materials and would not be 

appropriate for the aluminum horn. 

• While the bolt torque value or 

torque tube deformation could be a 

partial indicator, it is not a full measure 

of all the contributing factors. The 

viability of such a method would also be 

affected by manufacturing variability 

(machining, drawing tolerances, and so 

forth) making it difficult to build an 

appropriate model to ensure an 

adequate inspection method. 

We did not change this final rule AD 

action based on these comments. 

Request To Clarify What the AD 

Requires 

Dave Fitzgerald for the ICS requested 

we clarify the statement in the summary 

of the NPRM (76 FR 36395, June 22, 

2011) of what parts are being replaced. 

We agree with the commenter that it 

is important to clearly state what parts 

are required in the AD action. 

We changed the summary of the final 

rule to require replacement of the 

stabilator horn assembly and/or 

repetitive inspection of the stabilator 

horn assembly, as applicable. 

Request To Allow Re-Use of Inspected 

Horns 

Ivan R. Wilson, Patrick D. Donovan, 

Carl Schoolcraft, Andrew Detsch, and 

John F. Murray requested a change in 

compliance time to allow inspected 

parts to have the same inspection 

interval as new replacement parts. Carl 

Schoolcraft also requested the option of 

installing serviceable parts in lieu of 

new parts. 

We agree with allowing used parts as 

replacement parts provided they have 

been inspected before installation and 

found free of cracks (serviceable) and 

they continue the repetitive inspection 

option in this AD. However, we disagree 

with allowing the same interval on used 

inspected replacement parts as on new 

replacement parts because a single 

penetrant inspection method does not 

provide the same confidence level for a 

crack-free part as a new part does. Such 

an inspection could not reliably detect 

sufficiently small cracks; therefore, an 

approach similar to damage tolerance 

requiring multiple inspections is 

warranted. 

We added language to: 

• Clarify compliance and procedures 

for the replacement of the stabilator 

horn assembly with a serviceable 

stabilator horn assembly, provided it is 

inspected before installation and found 

free of cracks or corrosion and continues 

with the repetitive inspections required 

for a used part; and 

• Clarify the initial inspection for 

owner/operators who may have already 

installed a used serviceable stabilator 

horn assembly on their airplane. 

Request To Validate and/or Revise the 

Cost Estimate 

Randy Black and Arthur John Beyer 

requested we validate and/or revise the 

cost estimate. One commenter ordered 

parts including a new horn, new torque 

tube, new bearings, and new hardware 

estimated at $1,500 for only the parts 

cost. Another commenter noted the cost 

on U.S. operators does not include 

subsequent inspections. 

We do not agree with this request 

because the parts cost only includes 

those parts required by the AD actions 

(the horn assembly). Optional parts, 

such as the tube, are not mandated and 

not required in the associated cost. 

Repetitive inspections are not included 

in AD cost estimates as it cannot be 

determined which option an owner/ 

operator may choose, or the number of 

times the action(s) may be executed on 

an individual aircraft. 

We did not change this final rule AD 

action based on these comments. 

Request To Have Manufacturer Show 

Ability To Meet Parts Demand 

Commenters Bob Rosansky, Patrick D. 

Donovan, Patric Barry, John Trudel, and 

Phil Ciholas are associated with this 

request. Some commenters requested 

that the airplane manufacturer 

demonstrate the ability to meet the parts 

demand before the AD is issued. One 

commenter requested time to create a 

parts supply for the replacement horn 

from the Australian CASA STC SVA 

532. Several commenters estimated that 

it might require one year or more for the 

manufacturer to provide the required 

parts and are concerned that the 

manufacturer’s parts ordering system 

will be unable to meet the demand. The 

request for the CASA-approved horn is 

to alleviate the AD actions. 

We do not agree because the 

manufacturer has told the FAA they can 

support the parts requirements for this 

AD. This AD is necessary to address an 


tkelley on DSK3SPTVN1PROD with RULES
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unsafe condition. If parts availability 

becomes a problem, the FAA will 

consider AMOC requests and determine 

whether they provide an acceptable 

level of safety when they are submitted 

following the procedures in 14 CFR 

39.19 and this AD. The AD initial 

compliance time should provide 

sufficient time to create a parts supply. 

The AD is not addressing the CASAapproved horn since the horn is not 

FAA-approved at this time. 

We did not change this final rule AD 

action based on these comments. 

Request To Change Compliance Time 

Because Quality Issues Might Occur 

Patrick D. Donovan, Patric Barry, and 

John Trudel requested changes to the 

compliance time based on possible 

quality issues in manufacturing or 

delivering required parts. The 

commenters referenced instances where 

the manufacturer supplied parts that did 

not meet/specifications or delivered the 

wrong part numbers. 

We do not agree because if nonconforming parts or the wrong parts are 

distributed by the manufacturer, then 

the problem will be addressed through 

the current regulations, including 

potential AD action. The FAA cannot 

address this problem unless it occurs 

and is appropriately reported. 

We did not change this final rule AD 

action based on these comments. 

Request To Have Manufacturer Provide 

Parts Kit 

Randy Black suggested the 

manufacturer combine the replacement 

horn into a kit with the torque tube and 

noted that a combined kit would 

provide a convenience to owners/ 

operators. 

We disagree because the additional 

parts beyond the horn assembly are not 

required by this AD because they are not 

necessary to address the unsafe 

condition. 

We did not change this final rule AD 

action based on these comments. 

Request To Have FAA Directly Notify 

Owners/Operators of the NPRM (76 FR 

36395, June 22, 2011) 

Dennis Boykin stated the FAA failed 

to send the NPRM (76 FR 36395, June 

22, 2011) to him. The commenter stated 

he was not notified of the NPRM by the 

FAA, but by the type club. We conclude 

that the commenter requested direct 

notification of the NPRM. 

We disagree with the request. The 

FAA does not mail NPRMs. Effective 

March 1, 2010, the FAA stopped 

mailing paper copies of ADs. We have 

continued to fax and/or use the US 

Postal Service to mail Emergency ADs. 

To continue receiving ADs at no cost, 

please subscribe to our GovDelivery 

email service by visiting the Regulatory 

and Guidance Library home page 

(http://rgl.faa.gov). For those desiring 

paper copies, we will continue to 

provide the AD Biweekly, which is a 

paid subscription of all ADs issued in 

the Federal Register over the previous 

2-week period. The AD Biweekly is 

printed and mailed by the Government 

Printing Office (GPO). Contact the GPO 

directly at phone: (202) 512–1806 to 

subscribe. 

We did not change this final rule AD 

action based on these comments. 

Request To Include Reporting 

Requirement and Analysis of Data To 

Refine AD 

Kristin Amelia Winter, George 

Edward White, Patrick D. Donovan, 

Arthur John Beyer, Hans Neubert for the 

ICS, and Dennis Boykin requested 

adding a reporting requirement with 

subsequent use of the data to evaluate 

(or eliminate) the inspection intervals 

and to evaluate potential terminating 

actions. Two of the commenters 

requested the reporting be provided to 

both the FAA and ICS. One commenter 

also requested a provision for rescinding 

the AD or extending the inspection 

intervals based on the number of nonfindings, especially if a new part is 

installed. Finally, one commenter 

proposed to exclude the Model PA–24– 

260 and evaluate it at a later date. 

The commenters noted that the initial 

inspection cycle would provide three 

years of time to collect and evaluate the 

data which would allow the FAA and 

interested parties an opportunity to 

formulate a more narrowly targeted AD 

that would better balance the cost with 

the hoped for improvement in 

airworthiness and hence safety. Lastly, 

it would provide the data necessary to 

design and obtain approval of an AMOC 

or STC that effectively addresses this 

unsafe condition and terminates any 

final recurring AD. 

We disagree with adding a reporting 

requirement. Based on the Paperwork 

Reduction Act, a reporting requirement 

must meet the following conditions: 

• Help develop a corrective action; 

• Determine the scope of the problem 

and how adequate the Design Approval 

Holder’s corrective actions are; and 

• Avoid unsafe consequences if we 

do not collect the information. 

To eliminate the repetitive 

inspections and develop a terminating 

action depends on a combination of 

factors. The following three factors 

would require a re-design to eliminate 

the repetitive inspections: Balance arm 

interference fit, basic material 

properties, and use of a thicker torque 

tube previously discussed. Lowering the 

installation torque value was addressed 

earlier. Reduction of corrosion potential 

is currently addressed via repetitive 

inspections as discussed below. As all 

major contributing factors are not 

eliminated, reporting would not provide 

sufficient information to eliminate the 

inspections or directly provide 

terminating action. 

Any individual or group is free to 

work independently to coordinate data 

collection supporting a potential 

concept as an AMOC or design change 

(STC). 

We also disagree with evaluating the 

Model PA–24–260 airplane only in the 

future because that model meets the 

regulatory requirement where the unsafe 

condition is likely to exist or develop in 

other products of the same type design. 

We did not change this final rule AD 

action based on these comments. 

Request To Have FAA Determine Status 

of Type Certificate Holder 

Patric Barry and John Trudel 

expressed concern that the 

manufacturer ’s engineering/design 

work on the corrective action and parts 

supply issues are evidence of 

abandonment of the responsibilities of a 

type certificate holder. We conclude the 

commenters requested the FAA 

determine the status of the type 

certificate holder. 

We disagree with this request. The 

manufacturer met its obligation as a 

type certificate holder by working with 

the FAA and industry to generate a 

corrective action program addressing 

the unsafe condition. 

Based on these comments, we made 

no change to the AD action. 

Request To Require Inspection of the 

Torque Tube Assembly/Control Horn 

Hans Neubert for the ICS commented 

that the reason that the torque tube 

assembly/control horn has not been 

previously inspected for cracks is due to 

the fact there is no prior manufacturer 

requirement to inspect. We infer the 

commenter requested the FAA require 

inspection of the torque tube assembly/ 

control horn. 

We agree with the commenter. There 

was not a known need for inspection of 

the assembly. With discovery of the 

unsafe condition, a program is now 

being put into place. 

Based on these comments, we made 

no change to the AD action. 


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Request To Make Piper Aircraft, Inc. 

Service Bulletin No. 1189, dated April 

29, 2010, Only Advisory for the AD 

Hans Neubert for the ICS 

recommended that this service 

information be considered as advisory 

only to the corrective action. The 

commenter stated that the preliminary 

and final versions of the service 

information were based on an industry 

magazine article and were without 

substantiating data, field service history, 

or engineering evaluation. 

We disagree because the FAA 

independently evaluated all available 

data. We incorporated the intent of this 

service information into the AD, with 

the exception of adjustments to the 

applicability and compliance time. 

We did not change this final rule AD 

action based on these comments. 

Request To Incorporate Corrosion 

Preventive Measures in the AD 

George Edward White recommended 

incorporation of corrosion preventive 

measures into the AD. The commenter 

noted known corrosion issues on the 

adjacent torque tube. 

We disagree because corrosion 

preventive measures are already covered 

by the following documents and are not 

necessary to address the unsafe 

condition identified in this AD: 

• Piper Aircraft, Inc. Service Bulletin 

No. 1160, dated December 26, 2005, at 

http://www.piper.com/Company/

Publications/SB%201160%20Stab%20

Torque%20Tube%20Assy%20Insp.pdf; 

• Special Airworthiness Information 

Bulletin CE–04–88, dated September 15, 

2004, at http://rgl.faa.gov/Regulatory_

and_Guidance_Library/rgSAIB.nsf/0/

77fc29bb15c8a85b8625721f0052ecb4/

$FILE/CE-04-88.pdf; 

• AD 74–13–03, Amendment 39–2588 

(41 FR 17371, April 26, 1976), at 

http://rgl.faa.gov/Regulatory_and_

Guidance_Library/rgAD.nsf/0/

5CBFDEAB5E2AC41586256E12004

98F02?OpenDocument&Highlight=74- 

13-03; 

• AC 43.13–1B, Acceptable Methods, 

Techniques, and Practices—Aircraft 

Inspection and Repair, at http://www.

faa.gov/regulations_policies/advisory_

circulars/index.cfm/go/document.

information/documentID/99861; and 

• AC 43–4A, Corrosion Control for 

Aircraft, at http://rgl.faa.gov/

Regulatory_and_Guidance_Library/

rgAdvisoryCircular.nsf/list/AC%2043- 

4A/$FILE/AC%2043-4a%20.pdf. 

Based on these comments, we made 

no change to the AD action. 

Request To Require Inspection of the 

Tail of the Aircraft 

Patric Barry stated that periodically 

opening up the tail of the aircraft for 

inspection may be beneficial, suggesting 

that routine servicing of the entire area 

should be included in this AD. Dave 

Fitzgerald for the ICS stated that 

opening up the tail area for service of 

the trim drum, torque tube bearings, and 

associated areas is beneficial as part of 

normal maintenance, but is not part of 

this AD since the AD addresses the horn 

and torque tube and not associated 

components. 

We agree that maintenance of the trim 

drum, torque tube bearings, and 

associated areas is important but 

disagree with including it in this AD 

action. These components are not 

directly related to the unsafe condition 

so are not part of this AD. 

We did not change this final rule AD 

action based on these comments. 

Conclusion 

We reviewed the relevant data, 

considered the comments received, and 

determined that air safety and the 

public interest require adopting the 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 (76 FR 

36395, June 22, 2011) for correcting the 

unsafe condition; and 

• Do not add any additional burden 

upon the public than was already 

proposed in the NPRM (76 FR 36395, 

June 22, 2011) 

We also determined that these 

changes will not increase the economic 

burden on any operator or increase the 

scope of the AD. 

Costs of Compliance 

We estimate that this AD affects 3,100 

airplanes of U.S registry. 

We estimate the following costs to 

comply with this AD: 

ESTIMATED COSTS

Action Labor cost Parts cost Cost per 

product 

Cost on U.S. 

operators 

Stabilator horn assembly inspection 12 work-hours × $85 per hour = 

$1,020 

Not applicable ................................ $1,020 $3,162,000 

We estimate the following costs to do 

any necessary replacements that would 

be required based on the results of the 

proposed inspection. We have no way of 

determining the number of airplanes 

that might need this replacement: 

ON-CONDITION COSTS

Action Labor cost Parts cost Cost per 

product 

Stabilator horn assembly replacement ......................... 12 work-hours × $85 per hour = $1,020 ...................... $572 $1,592 

According to the manufacturer, some 

of the costs of this AD may be covered 

under warranty, thereby reducing the 

cost impact on affected individuals. We 

do not control warranty coverage for 

affected individuals. As a result, we 

have included all costs in our cost 

estimate. 

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 


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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, 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. 

§ 39.13 [Amended] 

■ 2. The FAA amends § 39.13 by adding 

the following new airworthiness 

directive (AD): 

2012–17–06 Piper Aircraft, Inc.: 

Amendment 39–17169; Docket No. 

FAA–2011–0639; Directorate Identifier 

2011–CE–016–AD. 

(a) Effective Date 

This AD is effective October 22, 2012. 

(b) Affected ADs 

None. 

(c) Applicability 

This AD applies to the following Piper 

Aircraft, Inc. airplanes, certificated in any 

category: 

(1) Model PA–24, serial numbers (S/Ns) 

24–1 through 24–3687, with horn part 

number (P/N) 20397–00 (assembly P/N 

20399) installed; 

(2) Model PA–24–250, S/Ns 24–1 and 24– 

103 through 24–3687, with horn P/N 20397– 

00 (assembly P/N 20399) installed; and 

(3) Model PA–24–260, S/Ns 24–3642 and 

24–4000 through 24–5034, with horn P/N 

20397–00 (assembly P/N 20399) installed. 

(d) Subject 

Joint Aircraft System Component (JASC)/ 

Air Transport Association (ATA) of America 

Code 27: Flight Controls. 

(e) Unsafe Condition 

This AD was prompted by reports of cracks 

developing in the stabilator horn assembly. 

We are issuing this AD to detect and correct 

corrosion or cracks in the stabilator horn 

assembly. Corrosion or cracks could lead to 

failure of the stabilator horn. Consequently, 

failure of the stabilator horn could lead to a 

loss of pitch control in flight. 

(f) Compliance 

Comply with this AD following Piper 

Aircraft, Inc. Service Bulletin No. 1189, dated 

April 29, 2010, within the compliance times 

specified in this AD, unless already done 

(does not eliminate the repetitive actions of 

this AD). 

(g) Inspection/Replacement 

(1) When a new stabilator horn assembly 

has been installed (during production or 

replacement) and the stabilator horn 

assembly reaches a total of 1,000 hours timein-service (TIS) or 10 years after installation, 

or within the next 100 hours TIS after 

October 22, 2012 (the effective date of this 

AD), whichever occurs later, do one of the 

following actions: 

(i) Initially inspect the stabilator horn 

assembly for corrosion or cracks. Repetitively 

thereafter inspect at intervals not to exceed 

500 hours TIS or 5 years, whichever occurs 

first. 

(ii) Replace the stabilator horn assembly 

with a new stabilator horn assembly. When 

the new stabilator horn assembly reaches a 

total of 1,000 hours TIS after replacement or 

within 10 years after replacement, whichever 

occurs first, you must do one of the actions 

in paragraph (g)(1) of this AD. 

(iii) Replace the stabilator horn assembly 

with a used serviceable stabilator horn 

assembly that has been inspected before 

installation and found free of cracks or 

corrosion. Repetitively thereafter inspect at 

intervals not to exceed 500 hours TIS or 5 

years, whichever occurs first. 

(2) When a used serviceable stabilator horn 

assembly that has been inspected before 

installation and found free of cracks or 

corrosion has been installed and the 

stabilator horn assembly reaches a total of 

500 hours TIS or 5 years after installation, or 

within the next 100 hours TIS after October 

22, 2012 (the effective date of this AD), 

whichever occurs later, do one of the 

following actions: 

(i) Initially inspect the stabilator horn 

assembly for corrosion or cracks. Repetitively 

thereafter inspect at intervals not to exceed 

500 hours TIS or 5 years, whichever occurs 

first. 

(ii) Replace the stabilator horn assembly 

with a new stabilator horn assembly. When 

the new stabilator horn assembly reaches a 

total of 1,000 hours TIS after replacement or 

within 10 years after replacement, whichever 

occurs first, you must do one of the actions 

in paragraph (g)(1) of this AD. 

(iii) Replace the stabilator horn assembly 

with a used serviceable stabilator horn 

assembly that has been inspected before 

installation and found free of cracks or 

corrosion. Repetitively thereafter inspect at 

intervals not to exceed 500 hours TIS or 5 

years, whichever occurs first. 

(3) If you do not know the total hours TIS 

on the stabilator horn assembly, within the 

next 100 hours TIS after October 22, 2012 

(the effective date of this AD) do one of the 

actions required in paragraph (g)(1)(i), 

(g)(1)(ii), (g)(1)(iii), (g)(2)(i), (g)(2)(ii), or 

(g)(2)(iii) of this AD. 

(4) If any corrosion or cracks are found 

during any of the inspections required in 

paragraph (g)(1)(i), (g)(1)(iii), (g)(2)(i), or 

(g)(2)(iii) of this AD, before further flight, you 

must replace the stabilator horn assembly as 

specified in paragraph (g)(1)(ii), (g)(1)(iii). 

(g)(2)(ii), or (g)(2)(iii) of this AD, as 

applicable. 

(5) For the bolts common to the torque tube 

and stabilator horn, install the nuts using a 

torque of 120–145 in.-lbs. for the actions 

required by paragraphs (g)(1), (g)(2), or (g)(3) 

of this AD. 

Note 1 to paragraph (g) of this AD: The 

stated torque value of 120–145 in.-lbs. 

includes friction drag from the nut’s locking 

element, which is assumed to be 60 in.-lbs. 

The installation torque can be adjusted 

according to the actual, measured friction 

drag. For example, if the friction-drag torque 

is measured to be 40 in.-lbs. (20 in.-lbs. less 

than the assumed value of 60 in.-lbs.), then 

the installation torque will be adjusted to be 

100–125 in.-lbs. of torque. 

(6) You may at any time replace the 

stabilator horn assembly with a new 

stabilator horn assembly, provided no 

corrosion or cracks were found during an 

inspection that would require replacement 

before further flight. When the new stabilator 

horn assembly reaches a total of 1,000 hours 

TIS after replacement or within 10 years after 

replacement, whichever occurs first, you 

must do one of the actions in paragraph (g)(1) 

of this AD. 

Note 2 to paragraph (g) of this AD: Piper 

Aircraft, Inc. Service Bulletin No. 1160, dated 

December 26, 2005; Special Airworthiness 

Information Bulletin CE–04–88, dated 

September 15, 2004, at http://rgl.faa.gov/ 

Regulatory_and_Guidance_Library/ 

rgSAIB.nsf/0/ 

77fc29bb15c8a85b8625721f0052ecb4/$FILE/ 

CE-04-88.pdf; and AD 74–13–03, 

Amendment 39–2588 (41 FR 17371, April 26, 

1976), are related to this AD action. For the 

attached torque tube, you may consider 

combining that inspection with the 

requirements of this AD. 

(h) Alternative Methods of Compliance 

(AMOCs) 

(1) The Manager, Atlanta Aircraft 

Certification Office (ACO), FAA, has the 


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Federal Register / Vol. 77, No. 180 / Monday, September 17, 2012 / Rules and Regulations 57001 

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 ACO, send it to the 

attention of the person identified in the 

Related Information section 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. 

(i) Related Information 

For more information about this AD, 

contact Gregory K. Noles, Aerospace 

Engineer, FAA, Atlanta ACO, 1701 Columbia 

Avenue, College Park, Georgia 30337; phone: 

(404) 474–5551; fax: (404) 474–5606; email: 

gregory.noles@faa.gov. 

(j) Material Incorporated by Reference 

(1) The Director of the Federal Register 

approved the incorporation by reference 

(IBR) of the service information listed in this 

paragraph under 5 U.S.C. 552(a) and 1 CFR 

part 51. 

(2) You must use this service information 

as applicable to do the actions required by 

this AD, unless the AD specifies otherwise. 

(i) Piper Aircraft, Inc. Service Bulletin No. 

1189, dated April 29, 2010. 

(ii) Reserved. 

(3) For Piper Aircraft, Inc. service 

information identified in this AD, contact 

Piper Aircraft, Inc., 2926 Piper Drive, Vero 

Beach, Florida 32960; telephone: (772) 567– 

4361; fax: (772) 978–6573; Internet: http:// 

www.piper.com/company/publications.asp. 

(4) You may view this service information 

at the FAA, Small Airplane Directorate, 901 

Locust St., Kansas City, Missouri 64106. For 

information on the availability of this 

material at the FAA, call (816) 329–4148. 

(5) You may view this service information 

that is incorporated by reference at the 

National Archives and Records 

Administration (NARA). For information on 

the availability of this material at NARA, call 

(202) 741–6030, or go to: http:// 

www.archives.gov/federal-register/cfr/ibrlocations.html. 

Issued in Kansas City, Missouri, on August 

20, 2012. 

John Colomy, 

Acting Manager, Small Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. 2012–22529 Filed 9–14–12; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2012–0071; Directorate 

Identifier 2012–NE–05–AD; Amendment 39– 

17191; AD 2012–18–14] 

RIN 2120–AA64 

Airworthiness Directives; Pratt & 

Whitney Canada, Auxiliary Power Units 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: We are adopting a new 

airworthiness directive (AD) for certain 

serial numbers of Pratt & Whitney 

Canada (P&WC) PW901A auxiliary 

power units (APUs) approved under 

Technical Standard Order TSO–C77A 

and installed on, but not limited to, 

Boeing 747–400 series airplanes. This 

AD requires modifications of the rear 

gas generator case, exhaust duct 

support, and turbine exhaust duct 

flanges. This AD was prompted by 

several events of high-pressure turbine 

blade fracture leading to separation of 

the rear gas generator case and release 

of high energy debris. We are issuing 

this AD to prevent separation of the rear 

gas generator case and release of high 

energy debris, which could result in 

injury and damage to the airplane. 

DATES: This AD becomes effective 

October 22, 2012. The Director of the 

Federal Register approved the 

incorporation by reference of certain 

publications listed in this AD as of 

October 22, 2012. 

ADDRESSES: The Docket Operations 

office is located at Docket Management 

Facility, U.S. Department of 

Transportation, 1200 New Jersey 

Avenue SE., West Building Ground 

Floor, Room W12–140, Washington, DC 

20590–0001. 

FOR FURTHER INFORMATION CONTACT: 

Mazdak Hobbi, Aerospace Engineer, 

New York Aircraft Certification Office, 

FAA, Engine & Propeller Directorate, 

1600 Stewart Avenue, Suite 410, 

Westbury, NY 11590; phone: 516–228– 

7330; fax: 516–794–5531; email: 

mazdak.hobbi@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Discussion 

We issued a notice of proposed 

rulemaking (NPRM) to amend 14 CFR 

part 39 to include an AD that would 

apply to the specified products. That 

NPRM was published in the Federal 

Register on February 27, 2012 (77 FR 

11421). That NPRM proposed to correct 

an unsafe condition for the specified 

products. Transport Canada, which is 

the aviation authority for Canada, has 

issued AD CF–2011–40, dated October 

26, 2011 (referred to after this as ‘‘the 

MCAI’’), to correct an unsafe condition 

for the specified products. The MCAI 

states: 

The PW901A Auxiliary Power Units have 

experienced several events of High Pressure 

Turbine (HPT) blade fracture, some of which 

have resulted in the separation of the rear gas 

generator case, exhaust duct support, the 

turbine exhaust duct flanges and the release 

of high energy debris. Subsequent 

investigation revealed the turbine exhaust 

duct can separate under excessive load 

conditions resulting from extreme engine 

distress such as HPT blade fractures. 

You may obtain further information by 

examining the MCAI in the AD docket. 

Comments 

We gave the public the opportunity to 

participate in developing this AD. We 

considered the comments received. The 

following presents the comments 

received on the proposal and the FAA’s 

response to each comment. 

Support for the NPRM 

The Boeing Company indicated it 

supported the content of the proposed 

rule. 

Request To Increase Compliance Time 

Several commenters believed the 

compliance time in the AD should be 

extended. Atlas Air requested that the 

compliance time be increased from 42 to 

60 months. Atlas Air noted that the 42- 

month requirement would force them to 

remove APUs prior to their 8,000 hours 

soft time threshold which is based on 

their budget and operating experience 

and reliability. This threshold would 

increase the maintenance burden and 

cost to Atlas Air. 

KLM Royal Dutch Airlines (KLM) also 

requested that the compliance date be 

extended. KLM indicated that requiring 

all the affected APUs be modified in 42 

months would require forced 

unscheduled replacements. 

United Airlines (UAL) also requested 

that the compliance time be extended 

from 42 to 48 months. United indicated 

that the 42-month compliance time 

would require engines to be removed 

prematurely and cause capacity 

problems for repair shops. 

We do not agree. We have no data that 

justifies extending the compliance time 

to 48 months. Operators who want to a 

longer compliance interval may request 

an AMOC using the procedures in 14 

CFR part 39. Operators contemplating 

an AMOC request are reminded that 

they must show that their extension will 


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