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A single pilot reports that on the first flight after maintenance repaired the exhaust system on their mooney M20K-305 aircraft; they noticed a hot/burning smell and the engine monitor alarm indicated a high and rapidly rising cylinder head temperature (cht). Exhaust manifold from cylinders was not fully fitted into the slip joint of the exhaust y-tube transition pipe causing smoke; extreme heating and melting of an engine cowling.
| Attributes | |
| ACN | 1235135 |
| Time | |
| Date | 201501 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | M-20 K (231) / Encore |
| Flight Phase | Initial Climb |
| Route In Use | None |
| Flight Plan | None |
| Component | |
| Aircraft Component | Engine Exhaust System |
| Person 1 | |
| Function | Pilot Flying Single Pilot |
| Qualification | Flight Crew Commercial Flight Crew Flight Instructor Flight Crew Instrument Flight Crew Multiengine |
| Experience | Flight Crew Last 90 Days 40 Flight Crew Total 2000 Flight Crew Type 615 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Procedural Maintenance Deviation - Procedural Published Material / Policy Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor |
Narrative:
The exhaust system on our mooney M20K-305 had been repaired and this was the first flight post maintenance. Shortly after takeoff; climbing through approx. 500 feet AGL; the engine monitor alarm indicated a high and rapidly rising cylinder head temperature (cht). Suspecting detonation/pre-ignition; power was reduced to minimum needed for level flight and a left turn to enter a downwind for runway 27 was started. At this point I noticed a hot/burning smell. A tight pattern was flown and the aircraft promptly landed. Exiting the aircraft; smoke was seen rising from the engine cowling near the air inlet. This was extinguished with a fire extinguisher and the cowling removed. The inside of the cowling was visibly damaged due to melting/extreme heating from what appeared to be the exhaust manifold. Post inspection revealed that the exhaust system had been improperly assembled. The exhaust manifold from the cylinders was not fully fitted into the slip joint of the exhaust y-tube transition pipe. It was approximately one inch out of place. This reduced the clearance between the exhaust and cowling causing the melting and smoking. Additionally; because the manifold was out of place; there was a small gap between the cylinder head and the exhaust manifold flanges. Exhaust leaks from this area potentially caused the high cht indication. In the future; a much more in-depth post maintenance inspection is necessary to prevent a recurrence.
Original NASA ASRS Text
Title: A single pilot reports that on the first flight after Maintenance repaired the Exhaust System on their Mooney M20K-305 aircraft; they noticed a hot/burning smell and the engine monitor alarm indicated a high and rapidly rising Cylinder Head Temperature (CHT). Exhaust manifold from cylinders was not fully fitted into the slip joint of the exhaust Y-tube transition pipe causing smoke; extreme heating and melting of an engine cowling.
Narrative: The exhaust system on our Mooney M20K-305 had been repaired and this was the first flight post maintenance. Shortly after takeoff; climbing through approx. 500 feet AGL; the engine monitor alarm indicated a high and rapidly rising Cylinder Head Temperature (CHT). Suspecting detonation/pre-ignition; power was reduced to minimum needed for level flight and a left turn to enter a downwind for runway 27 was started. At this point I noticed a hot/burning smell. A tight pattern was flown and the aircraft promptly landed. Exiting the aircraft; smoke was seen rising from the engine cowling near the air inlet. This was extinguished with a fire extinguisher and the cowling removed. The inside of the cowling was visibly damaged due to melting/extreme heating from what appeared to be the exhaust manifold. Post inspection revealed that the exhaust system had been improperly assembled. The exhaust manifold from the cylinders was not fully fitted into the slip joint of the exhaust Y-tube transition pipe. It was approximately one inch out of place. This reduced the clearance between the exhaust and cowling causing the melting and smoking. Additionally; because the manifold was out of place; there was a small gap between the cylinder head and the exhaust manifold flanges. Exhaust leaks from this area potentially caused the high CHT indication. In the future; a much more in-depth post maintenance inspection is necessary to prevent a recurrence.
Data retrieved from NASA's ASRS site 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.