Because the original AD on the Eclipse 500, issued in June, referenced an incorrect docket number, the Federal Aviation Administration issued a correction citing a change in reference to Docket No. FAA-2007-28462. The AD requires operators to incorporate information into the Limitations section of the airplane flight manual (AFM) that will require operation only in day visual flight rules (VFR), allow only a VFR flight plan, and maintain operation with two pilots. The day VFR limitation will prohibit flight at night because it is more difficult to avoid inadvertent flight into IMC at night.
The order stems from three instances of loss of primary airspeed indication from freezing condensation within the pitot system which could cause the stall warning to become unreliable and the stick pusher, overspeed warning, and autopilot to not function.
FAA’s concern was heightened by the aerodynamic characteristics of the Eclipse Model EA500 airplane, which relies on the stall warning and the stick pusher to alert the pilot prior to the loss of aircraft control. The standby airspeed is reliable and not affected by this failure mode. A temporary AFM revision prohibits operation in instrument meteorological conditions (IMC), requires two pilots, and limits the airspeed and altitude envelope if the event occurs in flight. The AFM limitations and FAA operational rules allow Model EA500 flight crews to file an instrument flight rule (IFR) flight plan even though the airplane is not approved for flight in IMC. This potentially causes an undue workload burden and confusion when the pilot has to refuse any instructions that take them into IMC.
“We are issuing this AD to prevent an unsafe condition when Air Traffic Control's (ATC's) ability to maintain traffic separation is compromised because an airplane on an IFR flight plan cannot accept a flight plan into IMC,” said the agency.
This is considered interim action. Eclipse is working on a modification to the pitot system. The agency will likely take on additional rulemaking and terminate the limitations when Eclipse completes the design modification to the pitot system and the FAA approves it.