Date: 201310
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Night
Aircraft: M-20 F Executive 21
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Cruise
Aircraft component: Reciprocating Engine Assembly
Component problem: Malfunctioning
Reporter organization: Personal
Reporter function: Technician
Reporter qualification: Maintenance Inspection Authority; Maintenance Powerplant; Maintenance Airframe
Human factors: Situational Awareness; Confusion
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Aircraft Aircraft Damaged; Flight Crew Diverted; General Maintenance Action
Contributing factors: Procedure; Human Factors; Incorrect / Not Installed / Unavailable Part
Primary problem: Incorrect / Not Installed / Unavailable Part

Narrative: Cylinders were removed and sent out for inspection. Upon return; cylinders were preassembled; rocker arms had been installed. Cylinders were installed onto crankcase and rocker arms were removed one at a time to install push rods; tappet plunger assemblies; pushrod tubes and seals. Dry Tappet Clearance Check was performed and found within limits. Engine run-up; Leak Check and Break-in all appeared normal. After 25-hours; the oil was drained and the filter and suction screen were inspected. No contamination was noted; therefore; the rocker covers were not removed. I found upon inspection after an emergency landing; the rocker arms on the # 2 and # 3 cylinders to be improperly assembled. The # 2 cylinder had two exhaust rocker arms installed and the # 3 cylinder had two intake rocker arms. The Part Numbers (P/N) were hard to read on some of the rocker arms. Because the rocker arms were improperly assembled; there was contact between the pushrod and the rocker arm during operation that wore away pushrod material to the point of failure on the # 3 cylinder. The # 3 cylinder was removed and inspected. All rocker arms were replaced and damaged rods were also replaced. Dry Tappet Clearance [Check] was redone on all cylinders. Engine run up and Leak Check will be completed. A test flight will also be completed.

Callback: Reporter stated he performed the cylinder installations on the turbo-charged Lycoming IO-360 engine approximately three months prior to his January 2014 in-flight Emergency. He was at 6;500 FT; night time VFR when the # 3 cylinder exhaust pushrod tip end broke and closed the exhaust valve. The effect was immediate on the aircraft. He thought someone had slammed on the brakes in flight. That was the effect of losing just one cylinder.  Even though air and fuel was going into the cylinder and ignition was occurring; the # 3 cylinder was dead; but the vibration was quite strong. He decided to cut the turbocharger to see if the vibration could be reduced and power went down; requiring moving the throttles up; while trying to balance the engine vibration.Reporter stated he extended the electric landing gear and declared an emergency. He noticed how quite the comm radio became after he declared his emergency.  ATC's response was immediate and their help was continuous. He can't thank them enough for directing him to another airport after the first alternate airport's pilot controlled runway lighting did not respond and he had to divert to a second alternate. The engine never overtemped.Reporter stated inspection of the engine showed metal chips in the rocker cover. The # 3 cylinder stayed on the engine. Although the exhaust push rod had failed; the rod remained inside the tube. An intake rocker arm had been installed where the exhaust rocker arm should have been. # 2 cylinder had an exhaust rocker arm at the intake rocker arm position. He doesn't remember if he re-installed the rocker arms and push rods as received from the cylinder repair facility; or if he; had actually mixed-up the intake and exhaust rocker arms. He does remember the difficulty in determining the part markings on some of the exhaust and intake rocker arms.



Synopsis: Three months after installing repaired cylinders on a turbocharged IO-360 Lycoming engine; pilot experiences loss of # 3 cylinder and strong engine vibrations at 6;500 FT; night time VFR. Emergency declared and pilot notes that ATC's help and support was wonderful in getting the Mooney M20F aircraft to an alternate airport. An exhaust push rod had failed due to an intake rocker arm had been installed at the # 3 cylinder exhaust rocker arm position.