Narrative:

1) in may 2005; 2 cylinders (#1 and #3) from the right engine ([teledyne continental motors] tcm-io-470L engine) of beechcraft baron were rejected for low compression (leaking exhaust valves). The 2 cylinders were removed and delivered to a local engine shop for repair or replacement as necessary. They reported that both cylinders had excessive cylinder ring steps and were rejected. Subsequently supplied us with 2 overhauled cylinders to replace the 2 faulty cylinders. These overhauled cylinders were installed on the right engine. Engine post maintenance run-ups (following installation) were without incident. 3 annual inspections and a service clinic inspection by a tcm field representative; plus more than 300 hours of flight time; occurred before incident. 2) in february 2009; our shop was informed that the right engine of beech baron had emitted excessive smoke during takeoff from ZZZ1 airport in january 2009. The beech baron immediately returned to airport for landing. The right engine was subsequently removed by an FBO based at ZZZ1 airport. The engine was then sent to overhaul shop at ZZZ2 for investigation. Shop found that one of the pistons in a cylinder that we had replaced in may 2005 had developed a hole. Shop estimates the hole in this piston was caused by pre-ignition. Shop further found the 2 cylinders (#1 and #3) that were replaced in may 2005 were of the wrong type for this engine. These 2 cylinders were for an O-470 engine; not an io-470 engine. These cylinders featured shorter spark plug holes than the proper cylinders for an io-470L engine. The spark plugs installed in these 2 cylinders were those called out by tcm for an io-470L engine. Unfortunately; since the 2 cylinders installed in may 2005 had shorter spark plug holes designed for shorter spark plugs; the spark plugs in those 2 cylinders extended deeper into the cylinder and could thus run hotter than normal. The result was probably a hot spot on one of these plugs that caused destructive pre-ignition which burned a hole in 1 piston. 3) the cause of this incident was installation of the wrong cylinders on the subject engine. Our shop gave the rejected cylinders to local engine shop who subsequently replaced them with overhauled cylinders. The cylinders we received from local engine shop were incorrect for this application. We had inadequate technical data to determine if we had received the proper cylinders. Our documentation; consisting of tcm parts and maintenance manuals; addresses tcm part numbers. The documentation provided by local engine shop stated the overhauled cylinders were class 68 cylinders. This may have meaning for some engine shops; but is not meaningful to an aircraft shop with exposure to only tcm manuals. Tcm technical support does not recognize the term 'class' either. 4) corrective action for this situation involves insisting the engine shop performing cylinder work have a complete description of the engine model for which a faulty cylinder has been removed. Also; engine shops will henceforth be required to identification the tcm part number of any cylinder that is returned to our aircraft shop.

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Original NASA ASRS Text

Title: A Lead Mechanic with Inspection Authorization (IA); reports his engine shop was informed the right engine of a Beech Baron had emitted smoke during takeoff; requiring immediate return to airport. Incident caused by previous installation of two incorrect cylinders.

Narrative: 1) In May 2005; 2 cylinders (#1 and #3) from the right engine ([Teledyne Continental Motors] TCM-IO-470L engine) of Beechcraft Baron were rejected for low compression (leaking exhaust valves). The 2 cylinders were removed and delivered to a local engine shop for repair or replacement as necessary. They reported that both cylinders had excessive cylinder ring steps and were rejected. Subsequently supplied us with 2 overhauled cylinders to replace the 2 faulty cylinders. These overhauled cylinders were installed on the right engine. Engine post maintenance run-ups (following installation) were without incident. 3 annual inspections and a service clinic inspection by a TCM Field Representative; plus more than 300 hours of flight time; occurred before incident. 2) In February 2009; our shop was informed that the right engine of Beech Baron had emitted excessive smoke during takeoff from ZZZ1 Airport in January 2009. The Beech Baron immediately returned to airport for landing. The right engine was subsequently removed by an FBO based at ZZZ1 Airport. The engine was then sent to overhaul shop at ZZZ2 for investigation. Shop found that one of the pistons in a cylinder that we had replaced in May 2005 had developed a hole. Shop estimates the hole in this piston was caused by pre-ignition. Shop further found the 2 cylinders (#1 and #3) that were replaced in May 2005 were of the wrong type for this engine. These 2 cylinders were for an O-470 engine; not an IO-470 engine. These cylinders featured shorter spark plug holes than the proper cylinders for an IO-470L engine. The spark plugs installed in these 2 cylinders were those called out by TCM for an IO-470L engine. Unfortunately; since the 2 cylinders installed in May 2005 had shorter spark plug holes designed for shorter spark plugs; the spark plugs in those 2 cylinders extended deeper into the cylinder and could thus run hotter than normal. The result was probably a hot spot on one of these plugs that caused destructive pre-ignition which burned a hole in 1 piston. 3) The cause of this incident was installation of the wrong cylinders on the subject engine. Our shop gave the rejected cylinders to local engine shop who subsequently replaced them with overhauled cylinders. The cylinders we received from local engine shop were incorrect for this application. We had inadequate technical data to determine if we had received the proper cylinders. Our documentation; consisting of TCM parts and maintenance manuals; addresses TCM part numbers. The documentation provided by local engine shop stated the overhauled cylinders were class 68 cylinders. This may have meaning for some engine shops; but is not meaningful to an aircraft shop with exposure to only TCM manuals. TCM technical support does not recognize the term 'class' either. 4) Corrective action for this situation involves insisting the engine shop performing cylinder work have a complete description of the engine model for which a faulty cylinder has been removed. Also; engine shops will henceforth be required to ID the TCM part number of any cylinder that is returned to our aircraft shop.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.