Flight Crew Instrument; Flight Crew Private
Flight Crew Last 90 Days 25.7; Flight Crew Total 1809.6; Flight Crew Type 771.4
Confusion; Human-Machine Interface; Troubleshooting; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Aircraft Equipment Problem Dissipated; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification; General Declared Emergency
Aircraft; Human Factors; Weather
My wife; daughter and I were returning home in our A36 turbo-normalized Bonanza. We tried unsuccessfully to top some weather at FL230 and picked up light rime on the leading edges even with the TKS (wing weeping de/anti-ice) system running; so I elected to request and was cleared to descend to 11;000 where the OAT was around +1C according to the engine monitor data. Based on the forecasts I had reviewed prior to the flight I believed there was no significant icing risk but encountered icing nonetheless.After leveling at 11;000 I left the power at my descent settings because we were in bumpiness for a bit. The ice we had collected was shedding from the leading edges with the TKS system running in deice mode. I did not observe any more ice building on the tip tanks or other unprotected surfaces. We finally reached smoother air; although we were still in IMC; and I decided to increase the power for a faster cruise. I pushed the mixture to full rich and the prop from 2300 to 2500 RPM; intending to pull the mixture back LOP while observing the engine monitor. I wanted to observe the monitor as I leaned because something about the engine just didn't feel right. The throttle was wide open and the boost pump was off. Pushing the mixture full rich flooded the engine. A wiser pilot would probably have immediately leaned the mixture again but I was not that wise. We were instead without power in IMC for approximately 90 seconds according to the engine monitor data I later reviewed. The data also shows that for the two minutes before I pushed the mixture full rich the fuel flow had decreased from 15 to 12 GPH; which I had not noticed but probably contributed to my sense that the engine was not right. I think the reduced fuel flow was due to reduced air flow resulting from ice collecting on the induction air filter. After losing power; my daughter in the right seat pointed out that the alternate air door light had illuminated; indicating that the door had opened. (The light is obscured by the control arm when setting in the left seat unless you lean your head to the right.) I disconnected the autopilot after seeing that the airspeed had dropped to 80 KTS; then pitched for best glide speed while declaring an emergency with Center; identifying the nearest suitable airport 8 miles away (a 3;100 FT runway at 540 MSL elevation) and starting a turn toward it. I switched tanks for good measure then tried pulling the mixture back which restarted the engine. By the time we leveled off after the restart we were somewhere around 7;500. I was cleared down to 7;000 then direct to our destination after letting ATC know that we again had power. The alt air door light remained illuminated for a few minutes then went off. The OAT at 7;000 was about +4C.
The pilot of a well equipped BE36 encountered icing at FL230 and descended to 11;000 expecting to exit icing conditions. Instead he suffered engine failure when he selected full rich mixture before attempting to lean the mixture. A subsequent leaning of the mixture affected a recovery of engine power and the flight continued to its original destination.