FAA has issued AD 2018-02-04 Aerospace Welding Minneapolis, Inc. applicable on Muffle installed on Cessna 172R/S. Effective Date of this AD is February 21, 2018Muffler part No. A1754001-23 172R S/Ns 80001 and up; 172S S/Ns 8001 and up Muffler part No. A1754001-25 172R S/Ns 80001 and up; 172S S/Ns 8001 and up; 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. Compliance :Comply with this AD within the compliance times specified, unless already done.Inspection of the Muffler (1) Within 5 hours time-in-service after February 21, 2018, inspect the affected muffler following the instructions listed in paragraphs (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 (1) , within 5 hours after February 21, 2018, you may remove and replace the affected muffler. (3) If replacement specified in paragraph (2) is done instead of the inspection required in paragraph (1) , then paragraph (3) is the only additional requirement. Replacement of the Muffler (1) If evidence of breaches (leakage) is found during the inspection required , 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 muffle (2) If no evidence of breaches (leakage) is found during the inspection required of this AD, within the next 100 hours TIS after February 21, 2018 or at the next annual inspection, whichever occurs later, remove. (3) After February 21, 2018, do not install on any airplane an affected muffler.
This AD 2017-16-11 requires an inspection of connecting rods and replacement of affected connecting rod small end bushings. AD was prompted by several reports of connecting rod failures resulting in uncontained engine failure and in-flight shutdowns (IFSDs). AD applies to: (1) All Lycoming Engines reciprocating engines listed in Table 1 of Lycoming Engines MSB No. 632B, dated August 4, 2017, and
(2) all Lycoming Engines reciprocating engines that were overhauled or repaired using any replacement part listed in Table 2 of Lycoming MSB No. 632B, which was shipped from Lycoming Engines during the dates listed in Table 2 of Lycoming MSB No. 632B.
Reason of this AD is reports of uncontained engine failures and IFSDs due to failed connecting rods on various models of Lycoming Engines reciprocating engines listed in Table 1 of Lycoming MSB No. 632B, that were overhauled or repaired using any replacement part listed in Table 2 of Lycoming Engines MSB No. 632B, which was shipped from Lycoming Engines during the dates listed in Table 2 of Lycoming Engines MSB No. 632B.
This AD requires accomplishing the instructions in MSB describing procedures for inspecting connecting rods and replacing connecting rod small end bushings to prevent connecting rod failure. If not complied, could result in uncontained engine failure, total engine power loss, IFSD, and possible loss of the airplane.
Lycoming has determined that a small percentage of the bushings manufactured by a sub-supplier during a specific time period were diametrically undersized, resulting in a tightness of fit below factory accepted tolerances.These non-conforming bushings may have a substantially lower push-in/pull-out force than conforming bushings and may be susceptible to unseating during normal engine operations.
(1) For all affected engines, within 10 operating hours after the effective date of this AD, inspect all affected connecting rods as specified in MSB.
(2) Replace all connecting rods that fail the inspection required by this AD with parts eligible for installation.