GA small aircraft pilot experiences premature gear retraction on takeoff.

Attributes
ACN	170558
Time
Date	199102
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz
State Reference	US
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : smf
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	climbout : takeoff ground : preflight
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument pilot : commercial pilot : cfi
Experience	flight time last 90 days : 30 flight time total : 325 flight time type : 250
ASRS Report	170558
Person 2
Affiliation	Other
Function	observation : passenger
Qualification	pilot : private
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Following the completion of the annual inspection, the landing gear knob was left in the up position (most likely due to the emergency landing gear destination during the arrival). Aircraft is equipped with an airspeed activated micro switch which prevents gear retraction while the aircraft is on the surface, ostensibly. Complete preflight was conducted according to the aircraft pilot operating handbook to include a check of the gear knob being down. However, the pilot looking at the knob did not mentally register the situation--most likely due to down and locked indications; i.e., green light and gear indicator. Aircraft was accelerated down the runway, and at an airspeed of approximately 60 mph the landing gear retracted and the aircraft settled on the runway. As a result, no substantial damage occurred to the aircraft, and no injuries occurred to any individuals. It should be noted that the pilot operating handbook recommends rotation at an airspeed of 65-76 mph. Correction action would be the utilization of a higher airspeed in designing the micro switch (possibly a speed between the high end of rotation speed and vx). More preferable would be utilization of a pressure sensitive or weight sensitive design as found in other aircraft makes.

Original NASA ASRS Text

Title: GA SMA PLT EXPERIENCES PREMATURE GEAR RETRACTION ON TKOF.

Narrative: FOLLOWING THE COMPLETION OF THE ANNUAL INSPECTION, THE LNDG GEAR KNOB WAS LEFT IN THE UP POS (MOST LIKELY DUE TO THE EMER LNDG GEAR DEST DURING THE ARR). ACFT IS EQUIPPED WITH AN AIRSPD ACTIVATED MICRO SWITCH WHICH PREVENTS GEAR RETRACTION WHILE THE ACFT IS ON THE SURFACE, OSTENSIBLY. COMPLETE PREFLT WAS CONDUCTED ACCORDING TO THE ACFT PLT OPERATING HANDBOOK TO INCLUDE A CHK OF THE GEAR KNOB BEING DOWN. HOWEVER, THE PLT LOOKING AT THE KNOB DID NOT MENTALLY REGISTER THE SITUATION--MOST LIKELY DUE TO DOWN AND LOCKED INDICATIONS; I.E., GREEN LIGHT AND GEAR INDICATOR. ACFT WAS ACCELERATED DOWN THE RWY, AND AT AN AIRSPD OF APPROX 60 MPH THE LNDG GEAR RETRACTED AND THE ACFT SETTLED ON THE RWY. AS A RESULT, NO SUBSTANTIAL DAMAGE OCCURRED TO THE ACFT, AND NO INJURIES OCCURRED TO ANY INDIVIDUALS. IT SHOULD BE NOTED THAT THE PLT OPERATING HANDBOOK RECOMMENDS ROTATION AT AN AIRSPD OF 65-76 MPH. CORRECTION ACTION WOULD BE THE UTILIZATION OF A HIGHER AIRSPD IN DESIGNING THE MICRO SWITCH (POSSIBLY A SPD BTWN THE HIGH END OF ROTATION SPD AND VX). MORE PREFERABLE WOULD BE UTILIZATION OF A PRESSURE SENSITIVE OR WT SENSITIVE DESIGN AS FOUND IN OTHER ACFT MAKES.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.