Eclipse works on moisture problem with pitot system

 - April 27, 2007, 11:21 AM

By the middle of last month, Eclipse Aviation had delivered two airplanes to individual owners and three to air-taxi operator DayJet, which is using its airplanes for pilot training. DayJet plans to certify installation of a stand-alone attitude indicator to make its first airplanes Part 135 compliant until Eclipse receives certification for a third ADAHRS.

Eclipse is also working on a fix for the model 500’s two pitot/AOA probes, which have three times had a problem with moisture freezing and caused the airspeed indication to wind down to zero, generating crew alert system messages on the avionics displays. The standby airspeed indicator is not affected.

Until the problem is resolved, Eclipse is limiting the jet to VMC conditions with an Eclipse company pilot or mentor pilot on board. Eclipse has found during tests that a pitot tube inside the TSO’d pitot/AOA probes can remain below freezing even with the pitot heater on. According to Eclipse, “It is believed that internal condensation, due to the departure from a high-humidity environment, may be collecting and freezing in the pitot tubing. This is causing trapped total pressure to the ADCs and, thus, a reduction and ultimate loss of airspeed indication.

“Only three instances of this failure have been recorded in more than 4,400 fleet hours, making this a rare occurrence. The Eclipse engineering team is investigating the cause of failure and working with the system supplier to determine the most expedient method of correction.”

In spite of the problem, Eclipse displayed the model 500 at two airshows in April: Sun ’n’ Fun in Lakeland, Fla., and the Aero German general aviation show in Friedrichshafen, its European debut. The airplane flown to Florida is the first-delivered airplane. It was leased back to Eclipse as a demonstrator.