DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0324; Directorate Identifier 2017-CE-004-AD]
RIN 2120-AA64

Airworthiness Directives; Aerospace Welding Minneapolis, Inc. Mufflers

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: We propose to adopt a new airworthiness directive (AD) for
certain Aerospace Welding Minneapolis, Inc. mufflers, part numbers
A1754001-23 and A1754001-25, installed on Textron Aviation Inc. (type
certificate previously held by Cessna Aircraft Company) Models 172,
172R, 172S, and 177 airplanes. This proposed 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 proposed AD would require
an inspection of the muffler for leaking to identify cracks and
replacement of the muffler. We are proposing this AD to correct the
unsafe condition on these products.

DATES: We must receive comments on this proposed AD by June 2, 2017.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:

Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the
instructions for submitting comments.

Fax: 202-493-2251.

Mail: U.S. Department of Transportation, Docket Operations, M-30, West
Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE.,
Washington, DC 20590.

Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.

For service information identified in this NPRM, 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 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.

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 the Docket Management Facility between 9 a.m. and
5 p.m., Monday through Friday, except Federal holidays. The AD docket
contains this proposed AD, the regulatory evaluation, any comments
received, and other information. The street address for the Docket
Office (phone: 800-647-5527) is in the ADDRESSES section. Comments will
be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Mark Grace, Aerospace Engineer, FAA,
Chicago Aircraft Certification Office, 2300 East Devon Avenue, Des
Plaines, IL 60018-4696; telephone: (847) 294-7377; fax: (847) 294-7834;
email: mark.grace@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under the ADDRESSES section. Include "Docket No. FAA-2017-0324;
Directorate Identifier 2017-CE-004-AD" at the beginning of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of this proposed AD. We will
consider all comments received by the closing date and may amend this
proposed AD because of those comments.

We will post all comments we receive, without change, to http://www.
regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this proposed AD.

Discussion

We were notified of broken or cracked welds in the connecting weld
of the muffler body to muffler cuff on certain Aerospace Welding
Minneapolis, Inc. (AWI) mufflers, part numbers (P/Ns) A1754001-23 and
A1754001-25 that were installed on Textron Aviation Inc. (type
certificate previously held by Cessna Aircraft Company) Models 172,
172R, 172S, and 177 airplanes. There have been 54 occurrences
identified by maintenance and 2 occurrences identified by the carbon
monoxide (CO) gas monitor warning system. This condition, if not
corrected, could lead to CO exhaust fumes entering the cockpit heating
system and result in inhibiting the pilot's ability to maintain control
of the airplane.

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. 16063001, dated June
30, 2015. The service bulletin describes how to identify the
installation of an affected muffler.

FAA's Determination

We are proposing this AD because we evaluated all the relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of the same type design.

Proposed AD Requirements

This proposed AD would require inspecting the muffler for leaking
to identify cracks and replacement of the muffler with an FAA-approved
part.

Differences Between This Proposed AD and the Service Information

The AWI service bulletin requires replacement of the muffler before
further flight. This proposed AD would require an inspection of the
muffler for leaking to identify cracks within 5 hours time-in-service
(TIS) after the effective date of the AD with replacement of leaking
mufflers before further flight. This proposed AD would allow 100 hours
TIS or at the next annual inspection for replacement of non-leaking
mufflers. The service bulletin also requires returning the affected
mufflers back to AWI, and this proposed AD does not require return of
the muffler. The actions of the proposed AD would take precedence over
the service information.

Costs of Compliance

We estimate that this proposed AD affects 171 mufflers installed on
airplanes of U.S. registry.

We estimate the following costs to comply with this proposed AD:

Estimated Costs

The proposed AD would affect 171 mufflers with parts manufacturer
approval; however, only 9 mufflers remain in service.

According to the manufacturer, some of the costs of this proposed
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.

Regulatory Findings

We determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would not
have a substantial direct effect on the States, on the relationship
between the national Government and the States, or on the distribution
of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify this proposed
regulation:

(1) Is not a "significant regulatory action" under Executive
Order 12866,

(2) Is not a "significant rule" under the 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.

The Proposed Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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):