Cessna 210 Centurion / Turbo Centurion 210C; 210D
Flight Crew Commercial
Distraction; Situational Awareness; Workload
Aircraft Equipment Problem Critical; Inflight Event / Encounter Weather / Turbulence
Aircraft Equipment Problem Dissipated; Flight Crew Requested ATC Assistance / Clarification; General Declared Emergency
Weather; Aircraft
After leveling in cruise and performing Cruise Checklist and filling [in] the data; the airspeed indicator very quickly dropped to zero. I immediately verified pitot heat was ON and cross checked all the instruments to verify the aircraft was in level flight. Although no icing had been encountered; I also turned on the TKS system since there was no airspeed indication to assist in detecting ice. I contacted Departure and declared an emergency. I queried the Controller about the weather conditions at my departure airport to minimize 'head down' time. I also queried the Controller about the weather at my destination because in my pre-flight weather planning; the destination weather was forecast to be significantly better than the departure airport. I decided to continue the flight because the destination weather forecast was almost VFR compared to the departure which was almost low IFR and the aircraft was configured and trimmed to maintain straight and level flight. After several minutes; the airspeed came alive and the needle spun almost instantly from 0 to 160 KTS. I canceled the emergency with Center and continued without any further issues with the indicator.
The reporter stated that this aircraft was written up several times for this type event and Maintenance eventually replaced the pitot heat switch; the airspeed indicator and the pilot tube. He has flown this aircraft since that event without problems but also not in icing conditions.
A C-210's airspeed failed in IMC at 5;000 FT with the pitot heat ON so the pilot declared an emergency but continued because destination weather was near VFR. The airspeed recovered after a short time.