Document ID: FAA-2017-0324-0006
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: Aerospace Welding Minneapolis, Inc., Mufflers
Posted Date: 2018-01-17T05:00Z

[Federal Register Volume 83, Number 11 (Wednesday, January 17, 2018)]
[Rules and Regulations]
[Pages 2354-2357]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-00479]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0324; Product Identifier 2017-CE-004-AD; Amendment 
39-19157; AD 2018-02-04]
RIN 2120-AA64

Airworthiness Directives; Aerospace Welding Minneapolis, Inc., 
Mufflers

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
Aerospace Welding Minneapolis, Inc. mufflers, part numbers A1754001-23 
and A1754001-25, installed on airplanes. This AD was prompted by 
occurrences of cracks or broken welds in the connecting weld of the 
muffler body to muffler cuff that may allow carbon monoxide exhaust 
fumes into the cockpit heating system. This AD requires an inspection 
of the muffler for leaking to identify cracks and replacement of the 
muffler. We are issuing this AD to address the unsafe condition on 
these products.

DATES: This AD is effective February 21, 2018.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of February 21, 
2018.

ADDRESSES: For service information identified in this final rule, 
contact Aerospace Welding Minneapolis, Inc. (AWI) 1045 Gemini Road, 
Eagan, Minnesota 55121; telephone: 651-379-9888; fax: 651-379-9889; 
internet: www.awi-ami.com. You may view this service information at the 
FAA, Policy and Innovation Division, 901 Locust, Kansas City, Missouri 
64106. For information on the availability of this material at the FAA, 
call (816) 329-4148. It is also available on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2017-
0324.

Examining the AD Docket

    You may examine the AD docket on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2017-
0324; or in person at Docket Operations between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays. The AD docket contains 
this final rule, the regulatory evaluation, any comments received, and 
other information. The address for Docket Operations (phone: 800-647-
5527) is Docket Operations, 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: Mark Grace, Aerospace Engineer, FAA, 
Chicago ACO Branch, 2300 East Devon Avenue, Des Plaines, IL 60018-4696; 
telephone: (847) 294-7377; fax: (847) 294-7834; email: 
[email protected].

SUPPLEMENTARY INFORMATION: 

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 by adding an AD that would apply to certain Aerospace Welding 
Minneapolis, Inc. (AWI) mufflers, part numbers A1754001-23 and 
A1754001-25, installed on airplanes. The NPRM published in the Federal 
Register on April 18, 2017 (82 FR 18265). The NPRM was prompted by 
reports of broken or cracked welds in the connecting weld of the 
muffler body to muffler cuff. There have been 54 occurrences identified 
by maintenance and 2 occurrences identified by the carbon monoxide (CO) 
gas monitor warning system. The NPRM proposed to require an inspection 
of the muffler for leaking to identify cracks and replacement of the 
muffler. We are issuing this AD to correct the unsafe condition on 
these products.

Comments

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

Request To Expand the Applicability

    An anonymous commenter requested we expand the applicability of the 
AD to include additional part number mufflers produced by the same 
manufacturer as the mufflers affected by this AD. The commenter thinks 
the additional part number mufflers may share some of the same 
materials, processes, and methods of assembly as the mufflers affected 
by this AD.
    We do not agree with this comment. We addressed this concern during 
the investigation of the unsafe condition. We found that the unsafe 
condition is related to a design change and was applicable to one 
manufacturing lot. The unsafe condition applies to only the part 
numbers and serial numbers affected by this AD.
    We have not changed this AD based on this comment.

Request To Prohibit the Installation of the Affected Muffler on Cessna 
172R and 172S Airplanes

    An anonymous commenter pointed out that that all 10 SDRs address 
the Models 172R and 172S airplanes. This commenter also asks how many 
of the 56 parts were installed on Cessna Models C172R and C172S 
airplanes. The commenter explains that (AWI) mufflers, part numbers 
A1754001-23 and A1754001-25, lack the reinforced ends and high 
temperature corrosion resistant material specified in FAR Part 
23.1125(a)(1). The material substitution

[[Page 2355]]

makes it less resistant to high temperature and corrosion than the 
original type-certificated product. Based on the comments, the FAA 
infers that the commenter wants the AD to prohibit the installation of 
the affected parts, regardless of serial number, specifically on the 
Cessna Models 172R and 172S airplanes.
    We do not agree with the implication that the installation 
prohibition should apply to all produced parts or only apply to the 
Cessna Model 172R and 172S airplanes. The unsafe condition resulted 
from a design change with a limited serial number effectivity and that 
is approved for installation on other models. We don't know how many 
parts are installed or could be installed in the future on the Cessna 
Models C172R and C172S airplanes. The current applicability captures 
all the potentially unsafe parts in the field. Concerns about material 
substitutions complying with 14 CFR 23.1125(a)(1) goes beyond the scope 
of this AD.
    We have not changed this AD based on this comment.

Request We Add an Exhaust Systems Inspection

    An anonymous commenter requested we issue an AD similar to a 
Transport Canada AD which requires an ongoing periodic pressure testing 
of the exhaust systems to help identify and reduce the risk of CO 
entering the cabin area.
    We do not agree with this comment. This AD addresses the identified 
unsafe condition on the affected mufflers by requiring removal of the 
affected mufflers from airplanes. A more general pressure testing of 
exhaust systems is beyond the scope of this AD.
    We have not changed this AD based on this comment.

Request To Make Spot Weld Procedures More Rigid

    An anonymous commenter requested we require parts manufacturer 
approval (PMA) spot weld procedures to be more rigid. The commenter 
stated that manually operated spot welding machines do not consistently 
control pressure, time, or frequency as required by weld schedules 
because the human operator controls those factors. It is almost 
impossible to meet the weld code without a computer aided machine.
    We do not agree with this comment. Regulating how spot welds are 
done goes beyond the scope of this AD. This AD addresses the identified 
unsafe condition on the affected mufflers by requiring removal of the 
affected mufflers from airplanes.
    We have not changed this AD based on this comment.

Request We Prohibit the Use of Less Heat Resistant Material

    An anonymous commenter requested we not allow the substitution of 
less heat resistant material for higher heat resistant material. There 
are a number of FAA-approved PMA articles in existence certified by 
Identicality or Test and Computation where less heat resistant 
materials have been substituted. In many cases these PMA articles are 
used as terminating action to ADs and undermine the basis of the AD.
    We do not agree with this comment. An applicant for a PMA must 
demonstrate compliance with the applicable regulations before the PMA 
is granted. This AD addresses the unsafe condition on the affected 
mufflers by requiring removal of the affected mufflers from airplanes. 
Changing the PMA process goes beyond the scope of this AD.
    We have not changed this AD based on this comment.

Request We Make Related Documents Available

    David McGhee requested we ensure documents related to the AD are 
readily available. Although requested several times by telephone and 
email, the commenter was unable to obtain a copy of related service 
information. This made review and comment on the proposed AD difficult.
    We agree with this comment. Related documents should be available 
for a timely review of the AD. The NPRM incorrectly cited the related 
AWI service bulletin as AWI Mandatory Service Bulletin No. 16063001, 
dated June 30, 2015. The correct citation should read AWI Mandatory 
Service Bulletin No. 15063001, dated June 30, 2015. We confirmed the 
availability of the related service bulletin with the document provider 
and confirmed the commenter received a copy prior to the close of the 
comment period.
    We changed this AD to use the correct citation based on this 
comment.

Request a Change to the Cost of Compliance

    David McGhee requested we add the cost to determine if the affected 
muffler is installed on the airplane to the estimated cost of the AD. 
The related service information estimated it would take 1 hour of labor 
to inspect the airplane to determine if the affected muffler is 
installed.
    We do not agree with this comment. The estimated cost of the AD 
applies specifically to addressing and correcting the unsafe condition. 
The FAA process for determining the cost of compliance does not include 
the initial determination of applicability. Also, for many airplanes, a 
review of the maintenance records will identify if the affected muffler 
is installed.
    We have not changed this AD based on this comment.

Request We Allow the Use of Other Service Information for Muffler 
Replacement

    David McGhee requested we revise the AD to allow the use of other 
service information for installing a replacement muffler. Operators may 
choose to install an FAA-approved muffler from a source other than AWI. 
The service information proposed in the NPRM may not be appropriate for 
mufflers produced by a different manufacturer.
    We agree with this comment. If an operator installs an FAA-approved 
muffler other than the AWI muffler, the installation instructions from 
that manufacturer should be used.
    We have revised the language in this AD to allow the use of the 
manufacturer's installation instructions for the specific muffler that 
is being installed.

Request We Revise the Subject Heading

    Thomas Nelson requested we revise the subject heading of the AD 
because it is not part of the company's name and implies the AD applies 
to all mufflers made by this company.
    We partially agree with this comment. We agree the subject header 
could more clearly define the specific mufflers this AD applies to; 
however, we disagree with revising the subject header. The subject 
header is intended as a general header and is not intended to include 
details that address the specifics of applicability. The Office of the 
Federal Register develops the guidelines for the format and structure 
of rulemaking documents for all federal agencies to follow.
    We have not changed this AD based on this comment.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
this final rule with the changes described previously and minor 
editorial changes. We have determined that these minor changes:
     Are consistent with the intent that was proposed in the 
NPRM for correcting the unsafe condition; and

[[Page 2356]]

     Do not add any additional burden upon the public than was 
already proposed in the NPRM.
    We also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this final 
rule.

Related Service Information Under 1 CFR Part 51

    We reviewed AWI Cessna 172 (Lycoming) Muffler Removal and 
Installation, Revision 01, January 17, 2017. The service information 
describes procedures for removing and replacing the affected mufflers. 
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

    We reviewed AWI Mandatory Service Bulletin No. 15063001, dated June 
30, 2015. The service bulletin describes how to identify the 
installation of an affected muffler.

Costs of Compliance

    We estimate that this AD affects 171 mufflers installed on 
airplanes of U.S. registry.
    We estimate the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
              Action                      Labor cost              Parts cost          product        operators
----------------------------------------------------------------------------------------------------------------
Inspection of muffler............  1 work-hour x $85 per     Not applicable.....             $85         $14,535
                                    hour = $85.
Replacement of the muffler.......  4 work-hours x $85 per    $350...............             690         117,990
                                    hour = $340.
----------------------------------------------------------------------------------------------------------------

    This AD affects 171 mufflers with PMA; however, only 9 mufflers 
remain in service.
    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 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.
    This AD is issued in accordance with authority delegated by the 
Executive Director, Aircraft Certification Service, as authorized by 
FAA Order 8000.51C. In accordance with that order, issuance of ADs is 
normally a function of the Compliance and Airworthiness Division, but 
during this transition period, the Executive Director has delegated the 
authority to issue ADs applicable to small airplanes, gliders, 
balloons, airships, domestic business jet transport airplanes, and 
associated appliances to the Director of the Policy and Innovation 
Division.

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD will not have a substantial direct effect on the States, 
on the relationship between the national government and the States, or 
on the distribution of power and responsibilities among the various 
levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

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

PART 39--AIRWORTHINESS DIRECTIVES

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):

2018-02-04 Aerospace Welding Minneapolis, Inc.: Amendment 39-19157; 
Docket No. FAA-2017-0324; Product Identifier 2017-CE-004-AD.

(a) Effective Date

    This AD is effective February 21, 2018.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Aerospace Welding Minneapolis, Inc. (AWI) 
mufflers listed in figure 1 of paragraph (c) of this AD that are 
installed on but not limited to the airplanes listed in figure 2 of 
paragraph (c) of this AD.

    Note 1 to paragraph (c) of this AD: You may use AWI Mandatory 
Service Bulletin No. 15063001, dated June 30, 2015, to identify if 
an affected muffler is installed on the airplane.

[[Page 2357]]

         Figure 1 of Paragraph (c) of This AD--Affected Mufflers
------------------------------------------------------------------------
         Muffler part No.                   Muffler serial Nos.
------------------------------------------------------------------------
A1754001-23......................  33553 through 33557; 34721 through
                                    34728; 35322 through 35329; 35670;
                                    38481 through 38485; 38584 through
                                    38586; and 38723 through 38727.
A1754001-25......................  32795 through 32800; 33558 through
                                    33569; 33779 through 33790; 34636
                                    through 34653; 34968 through 34984;
                                    35159 through 35176; 37903 through
                                    37906; 38174 through 38193; 38502
                                    through 38506; 38566 through 38575;
                                    and 38817 through 38836.
------------------------------------------------------------------------

        Figure 2 of Paragraph (c) of This AD--Affected Airplanes
------------------------------------------------------------------------
                                        Textron Aviation Inc. (type
         Muffler part No.          certificate previously held by Cessna
                                        Aircraft Company) airplanes
------------------------------------------------------------------------
A1754001-23......................  Model 172 Serial numbers (S/Ns)
                                    17259224 and up; Model 172R S/Ns
                                    80001 and up; and Model 172S S/Ns
                                    8001 and up.
A1754001-25......................  Model 172 S/Ns 17256513 and up; Model
                                    172R S/Ns 80001 and up; 172S S/N
                                    8001 and up; and Model 177 S/N
                                    1770001 and up.
------------------------------------------------------------------------

(d) Subject

    Joint Aircraft System Component (JASC)/Air Transport Association 
(ATA) of America Code 7820, Exhaust Noise Suppressor.

(e) Unsafe Condition

    This AD was prompted by occurrences of cracks or broken welds in 
the connecting weld of the muffler body to muffler cuff that may 
allow carbon monoxide (CO) exhaust fumes into the cockpit heating 
system. We are issuing this AD to prevent cracks in the connecting 
weld of the muffler body to muffler cuff that may allow CO fumes to 
enter the cockpit heating system and possibly inhibit the pilot's 
ability to maintain control of the airplane.

(f) Compliance

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

(g) Inspection of the Muffler

    (1) Within 5 hours time-in-service after February 21, 2018 (the 
effective date of this AD), inspect the affected muffler following 
the instructions listed in paragraphs (g)(1)(i) through (iii).
    (i) Using a vacuum cleaner with the hose attached to the blowing 
side of the vacuum (with the filter installed), attach the vacuum to 
the airplane tailpipe and seal securely.
    (ii) The vacuum will pressurize the system sufficiently for a 
soap solution to be brushed or applied from a spray bottle to the 
surface of the exhaust system.
    (iii) Inspect for evidence of breaches (leakage) in the system 
from cracks.
    (2) In lieu of doing the inspection required in paragraph (g)(1) 
of this AD, within 5 hours after February 21, 2018 (the effective 
date of this AD), you may remove the affected muffler following AWI 
Cessna 172 (Lycoming) Muffler Removal and Installation, Revision 01, 
January 17, 2017, and replace the affected muffler with an FAA-
approved part that is not a muffler listed in figure 1 of paragraph 
(c) of this AD following the manufacturer's instructions.
    (3) If replacement specified in paragraph (g)(2) of this AD is 
done instead of the inspection required in paragraph (g)(1) of this 
AD, then paragraph (h)(3) of this AD is the only additional 
requirement of this AD.

(h) Replacement of the Muffler

    (1) If evidence of breaches (leakage) is found during the 
inspection required in paragraph (g) of this AD, before further 
flight, remove the affected muffler following AWI Cessna 172 
(Lycoming) Muffler Removal and Installation, Revision 01, January 
17, 2017, and replace the affected muffler with an FAA-approved part 
that is not a muffler listed in figure 1 of paragraph (c) of this AD 
following the manufacturer's instructions.
    (2) If no evidence of breaches (leakage) is found during the 
inspection required in paragraph (g) of this AD, within the next 100 
hours TIS after February 21, 2018 (the effective date of this AD) or 
at the next annual inspection after February 21, 2018 (the effective 
date of this AD), whichever occurs later, remove and replace the 
affected muffler with an FAA-approved part that is not a muffler 
listed in figure 1 of paragraph (c) of this AD as described in 
(h)(1).
    (3) After February 21, 2018 (the effective date of this AD), do 
not install on any airplane an affected muffler listed in figure 1 
of paragraph (c) of this AD.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Chicago 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 ACO Branch, send it to the attention of the person 
identified in paragraph (j)(1) 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.

(j) Related Information

    For more information about this AD, contact Mark Grace, 
Aerospace Engineer, FAA, Chicago ACO Branch, 2300 East Devon Avenue, 
Des Plaines, IL 60018-4696; telephone: (847) 294-7377; fax: (847) 
294-7834; email: [email protected].

(k) 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) AWI Cessna 172 (Lycoming) Muffler Removal and Installation, 
Revision 01, January 17, 2017.
    (ii) Reserved.
    (3) For service information identified in this AD, contact 
Aerospace Welding Minneapolis, Inc. (AWI) 1045 Gemini Road, Eagan, 
Minnesota 55121; telephone: 651-379-9888; fax: 651-379-9889; 
internet: www.awi-ami.com.
    (4) You may view this service information at FAA, Policy and 
Innovation Division, 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/ibr-locations.html.

    Issued in Kansas City, Missouri, on January 8, 2018.
Melvin Johnson,
Deputy Director, Policy and Innovation Division, Aircraft Certification 
Service.
[FR Doc. 2018-00479 Filed 1-16-18; 8:45 am]
 BILLING CODE 4910-13-P