PA20 pilot is unable to abort takeoff from gravel runway in alaska and flips into adjacent river.

Attributes
ACN	674360
Time
Date	200510
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Piper Single Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	ground : takeoff roll
Flight Plan	None
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 10 flight time total : 1270 flight time type : 1225
ASRS Report	674360
Events
Anomaly	aircraft equipment problem : less severe excursion : runway ground encounters other other anomaly other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Consequence	other other other
Supplementary
Problem Areas	Flight Crew Human Performance Airport Aircraft
Primary Problem	Aircraft

Narrative:

While using an off airport remote local runway (gravel bar) during a takeoff roll; an usual noise was heard and airspeed was dramatically reduced. An attempt to abort the takeoff was decided. While applying the brakes; the aircraft skidded on gravel and sand into the yentna river and flipped upside down. Upon inspection after being removed from the water; it was noted that the belly access cover was partially open. I believe a rock or stick had made contact with a corner of the cover causing it to come open forcing a large volume of air into the tail section of the aircraft acting as a parachute or air brake. The runway was too short to get stopped before entering the water. The design of the cover probably works well as a nosewheel aircraft; but I think a modification for a tailwheel conversion with more screws would keep this cover in place. Although I have flown this aircraft for 25 yrs and used the same runway at least 75 times; this is the first time this cover has come open.

Original NASA ASRS Text

Title: PA20 PLT IS UNABLE TO ABORT TKOF FROM GRAVEL RWY IN ALASKA AND FLIPS INTO ADJACENT RIVER.

Narrative: WHILE USING AN OFF ARPT REMOTE LCL RWY (GRAVEL BAR) DURING A TKOF ROLL; AN USUAL NOISE WAS HEARD AND AIRSPD WAS DRAMATICALLY REDUCED. AN ATTEMPT TO ABORT THE TKOF WAS DECIDED. WHILE APPLYING THE BRAKES; THE ACFT SKIDDED ON GRAVEL AND SAND INTO THE YENTNA RIVER AND FLIPPED UPSIDE DOWN. UPON INSPECTION AFTER BEING REMOVED FROM THE WATER; IT WAS NOTED THAT THE BELLY ACCESS COVER WAS PARTIALLY OPEN. I BELIEVE A ROCK OR STICK HAD MADE CONTACT WITH A CORNER OF THE COVER CAUSING IT TO COME OPEN FORCING A LARGE VOLUME OF AIR INTO THE TAIL SECTION OF THE ACFT ACTING AS A PARACHUTE OR AIR BRAKE. THE RWY WAS TOO SHORT TO GET STOPPED BEFORE ENTERING THE WATER. THE DESIGN OF THE COVER PROBABLY WORKS WELL AS A NOSEWHEEL ACFT; BUT I THINK A MODIFICATION FOR A TAILWHEEL CONVERSION WITH MORE SCREWS WOULD KEEP THIS COVER IN PLACE. ALTHOUGH I HAVE FLOWN THIS ACFT FOR 25 YRS AND USED THE SAME RWY AT LEAST 75 TIMES; THIS IS THE FIRST TIME THIS COVER HAS COME OPEN.

Data retrieved from NASA's ASRS site as of January 2009 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.