Urges Caution Following Reports Of Incorrect Readings

Avionics manufacturer and OEM supplier Avidyne Corporation has issued an urgent 'Safety Alert' following reports of incorrect altitude and airspeed information being displayed on some Entegra EXP5000 Primary Flight Displays (PFDs) manufactured or serviced in the past seven months.

"Avidyne has received a limited number of field reports of PFDs displaying incorrect altitude and airspeed information," the manufacturer states. "None of these occurrences led to an accident or incident."

The company says these occurrences included incorrect display of information at system startup, including one or more of the following:

• Altitude significantly in error when compared to field elevation with local barometric correction setting entered on PFD.
• Altitude significantly in error when compared to backup altimeter with identical barometric correction settings on both.
• Non-zero airspeed (inconsistent with high winds or propwash from a nearby airplane) indicated at system startup.
• Altitude or airspeed indications that vary noticeably after startup under static conditions.
• Erroneous airspeed indications in combination with erroneous attitude indications.
• A steady or intermittent "red X" in place of the airspeed indicator, altimeter, VSI or attitude indicator.

Avidyne stresses aircraft exhibiting any of these incorrect indications should not be flown -- even if the indication only appears on startup, and later returns to normal. In such cases, "...the PFD should nonetheless be considered unreliable and the aircraft should not be flown," the company states.

The manufacturer also reiterates the need for pilots to be vigilant in conducting proper preflight and inflight checks of instrument accuracy -- including preflight checks of the accuracy of both the primary and backup altimeter against known airfield elevation and against each other, and verification of airspeed and other instrument indications against backup instrumentation, and real-world conditions, while inflight.

Should pilots encounter suspect PFD information while inflight, Avidyne urges pilots to contact ATC for assistance on determining correct altitude, attitude and airspeed -- while also keeping in mind the limitations of that information. Pilots who experience incorrect PFD readings are also urged to discontinue the flight at the earliest, safest opportunity to do so, and to stay out of instrument flight conditions.

"Avidyne has notified the FAA and its OEMs about these events, and Avidyne’s technical investigation is ongoing," the manufacturer states. "At this time, this issue is considered to affect all Avidyne Primary Flight Displays manufactured or serviced between July 27, 2007, and February 1, 2008."

The final list of affected PFDs may differ based on the results of Avidyne's investigation. Stay tuned.

FMI: www.avidyne.com