Date: 201701
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 20
Light: Daylight
Aircraft: Cessna 210 Centurion / Turbo Centurion 210C; 210D
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Utility / Infrastructure
Flight phase: Cruise
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Engine
Component problem: Failed; Malfunctioning
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Workload; Time Pressure; Troubleshooting
Anomaly: Aircraft Equipment Problem Critical; Ground Event / Encounter Gear Up Landing
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Evacuated
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: At approximately XA00; I was piloting our company assigned aircraft in conduct of aerial survey work; along with my passenger/sensor operator on board. While 3/4 into our third survey line; heading north bound; the aircraft began to experience a sudden partial loss of power. I began to take corrective action first by verification that the fuel selector was selected on and the fullest tank. Secondly; I advanced the mixture control towards the full rich position; but had to back off as the engine experienced further roughness. I then checked each magneto; left and right; but no significant change was evident. Oil pressure and temps were at their normal operating range; as well as CHT. There was a significant drop of EGT indicated. At this point; I decided it would be in our best interest to make a pre-cautionary return to our remote base; as the corrective action I took had no positive effect. While we were en route to our remote base; I asked for a received priority handling and explained our situation to Center. While we were approximately 8 miles Southwest from ZZZ; we experienced a further loss of power to the point where we were unable to sustain level flight (began a gradual descent) I then [notified ATC] and set our squawk code to 7700 and hit direct to ZZZ on our Garmin 430 GPS; which was the nearest airport. I circled the approach end of runway 17 until we were at an altitude where I could make a safe approach to land. At approximately 1200' I selected the gear handle lever to the down position; but there was no mechanical response present. With not enough power to level off to go around and no leeway of time to attempt pumping the gear handle down manually (as we still were gradually losing altitude) I decided to prepare for a belly up landing and focused on making the landing as smooth as possible without making the situation worse. After crossing the threshold of runway 17; I selected the fuel selector to the off position; mixture to idle cutoff; and turned the magnetos off. We skidded to a stop approximately 500' past the second 1;000' runway hash marks. We evacuated the aircraft without any injuries as emergency personnel responded to the event.




Synopsis: Pilot conducting aerial survey work in a single engine aircraft reported an in-flight event of partial power loss resulting in a forced landing at a nearby airport. Additionally the landing gear would not extend and with no ability to troubleshoot resulted in a gear up landing.