Airworthiness Directive · Amendment 39-19157 · Exhaust noise suppressor
Aerospace Welding Minneapolis, Inc., Mufflers
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.
| 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. |
| Muffler part No. | Textron Aviation Inc. (type 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. |
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.
(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.
(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.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Appliances and equipment
