Cessna Stationair/Turbo Stationair 6
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 33; Flight Crew Total 3100; Flight Crew Type 525
ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; General Maintenance Action
Procedure
This was a normal flight until leaning for cruise at 7;000. The EGT on all cylinders rose quicker than normal while leaning. Cylinder #6 EGT dropped to zero on the gauge and the engine began to run rough before reaching the normal 18 GPH cruise fuel flow. A second cylinder EGT dropped to zero with more roughness. Mixture was enriched without restoration of full power; engine roughness continued. Approach Control was advised of intent to land at an airport straight ahead and ten miles. Clearance to descend to 2;500 feet was provided. We broke out of the overcast and cancelled IFR with the field well within gliding distance. Controller asked if I wanted a phone number to report a safe landing. I should have declined or remembered the G1000 records ATC communications. Instead; I took the challenge to maneuver for a partial power landing and write down a phone number. Winds were 35 knots from the south and pushed us north of the airport so a no-power landing on the runway would not be possible. The engine responded with enough power to make the runway for an uneventful landing. The mechanical issue was a loose hose clamp on the turbocharger duct that allowed a significant loss of induction system pressure. Fuel [to] air ratios were compromised resulting in the partial loss of power. The mechanic has been briefed on the issue and was apologetic. He applied torque seal to the hose clamp threads even though it was torqued properly. This was following completion of a service bulletin for exhaust system disassembly and inspection. I fault myself for agreeing to write down a phone number while maneuvering; pilot egos often overload themselves. Perhaps controllers should not solicit information below 2;500 feet AGL in such circumstances.
Cessna Stationair experienced partial engine power loss during cruise and made a precautionary landing at nearby airport.