Aerohack

Anyone know anything about two recent incidents involving Citation Excels that suffered some skin buckling as a result of out-of-trim pitch excursions when their crews failed to retract flaps after take-off and the autopilots tripped out? One was a NetJets Europe aircraft out of Geneva, the other the Swiss Government's Excel, airport unknown.

rightbank

Cessna have issued a memo concerning these two incidents. It appears that the crews ommitted to retract the flaps at the normal time and only did so later whilst doing 250-260kts (flap limiting speed 200kts).

The Excel has a movable two position stabiliser which moves according to the flap position. With the flaps up the stabiliser is in the cruise position, but is in the take-off position for all other flap settings.

According to data from the FDR, it seems that when the flaps where retracted the resulting stabiliser movement at such a relatively high speed caused an abrupt pitch down.

To stop further incidents, Cessna recommend that in similar circumstances the aircraft speed be reduced to below 200 kts prior to flap retraction. Eventually a flap/stabiliser overspeed advisory system will be incorporated.

vmommo

For fun try this in an Excel!

In clean configuration trim to 200 knots. Hands off select Flaps 7 and watch what happens! It's a fun ride, but make sure you have a block of airspace to play with.