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:
mark.grace@faa.gov.
SUPPLEMENTARY INFORMATION:
Discussion
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR
part 39 by adding an AD that would apply to certain 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 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
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
Action |
Labor cost |
Parts cost |
Cost per product |
Cost on U.S. operators |
Inspection of muffler |
1 work-hour x $85 per hour =
$85 |
Not applicable |
$85 |
$14,535 |
Replacement of the muffler |
4 work-hours x $85 per hour =
$340 |
$350 |
690 |
117,990 |
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
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive (AD):
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