Harco Probes Still Causing Eclipse Airspeed Problems

 - September 10, 2008, 12:41 PM

The FAA yesterday issued Airworthiness Directive 2008-19-01 warning that some Harco Labs pitot/angle-of-attack (AOA) probes are causing airspeed disagree caution indications in Eclipse 500 VLJs due to blockage within the pitot/AOA system from freezing condensation. Last year, the FAA issued AD 2007-13-11 because of a similar problem, and Eclipse Aviation issued a service bulletin to address the issue. According to the latest AD, “This blockage could lead to the stall warning becoming unreliable and [cause] the stick pusher, overspeed warning, autopilot and yaw damper to malfunction.” The new AD becomes effective on September 29. Actions required include a logbook check for applicable serial number Harco pitot/AOA probes and, if one of the applicable probes is installed or the serial number can’t be determined, limiting the airplane to day VFR flight and VFR flight plans. A test procedure is available in a Harco service bulletin, and passing the test removes the VFR limitation. Failure of the test mandates replacement of the probe. The VFR flight plan limitation appears to be the FAA’s attempt to prevent Eclipse pilots from filing and flying under IFR flight plans in visual meteorological conditions, which occurred during last year’s probe episode.