Collapse of left main gear.

Attributes
ACN	294903
Time
Date	199501
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : teb
State Reference	NJ
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Aircraft 1
Controlling Facilities	tower : clt
Operator	general aviation : instructional
Make Model Name	PA-31 Navajo Chieftan/Mojave/Navajo T1020
Operating Under FAR Part	Part 91
Flight Phase	landing other
Flight Plan	VFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : cfi pilot : commercial pilot : atp
Experience	flight time last 90 days : 60 flight time total : 11000 flight time type : 15
ASRS Report	294903
Person 2
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Events
Anomaly	aircraft equipment problem : critical other anomaly
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	none taken : unable
Consequence	other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Took off from teb for pleasure flight. Contacted swf for a touch and go. Got right main not locked down indication (no right green light) and red 'gear unlocked' light on. Abandoned approach, recycled gear once -- same indications. Recycled again -- got all 3 gear down and locked indication. Flew aircraft back to teb with all 3 gears down and locked as indicated. At teb, on downwind, checked gear down (3 green). Final gear check still 3 green. Touched down, let nose down, started deceleration. At approximately 50- 60 KTS, gear unsafe horn came on, left main gear collapsed, the aircraft skidded, swerving left for approximately 75-100 ft onto the grass and stopped. Right main and nosewheel stayed down and locked. At this point, I pulled all engine levers aft, shut off master and fuel, and exited the aircraft. Puzzling elements -- first, right main showing not down and locked at swf. Second, left main collapsed after all down and locked indication. Temperature was approximately 20 degrees F. Personally suspect gear selector lever malfunction or strut failure. Callback conversation with reporter revealed the following information: reporter was called to see if anything had been determined why the left gear collapsed. He stated that this type of failure had happened before on piper twin aircraft but had no definite facts to back up that statement. Although exact cause of failure has not been determined, it is suspected that engine exhaust affects a rubber grommet that helps to assure gear is in locked position. Aircraft was put on jacks and gear lowered. The gear went to locked position as it should. Problem is, the gear retracted during rollout at about 50-60 KTS. Reporter believes the aircraft will be totaled as it was an older model of the navajo. With the gear collapse, the propeller was bent and complete engine teardown will have to be accomplished. That work alone is estimated to be worth more than market value of aircraft.

Original NASA ASRS Text

Title: COLLAPSE OF L MAIN GEAR.

Narrative: TOOK OFF FROM TEB FOR PLEASURE FLT. CONTACTED SWF FOR A TOUCH AND GO. GOT R MAIN NOT LOCKED DOWN INDICATION (NO R GREEN LIGHT) AND RED 'GEAR UNLOCKED' LIGHT ON. ABANDONED APCH, RECYCLED GEAR ONCE -- SAME INDICATIONS. RECYCLED AGAIN -- GOT ALL 3 GEAR DOWN AND LOCKED INDICATION. FLEW ACFT BACK TO TEB WITH ALL 3 GEARS DOWN AND LOCKED AS INDICATED. AT TEB, ON DOWNWIND, CHKED GEAR DOWN (3 GREEN). FINAL GEAR CHK STILL 3 GREEN. TOUCHED DOWN, LET NOSE DOWN, STARTED DECELERATION. AT APPROX 50- 60 KTS, GEAR UNSAFE HORN CAME ON, L MAIN GEAR COLLAPSED, THE ACFT SKIDDED, SWERVING L FOR APPROX 75-100 FT ONTO THE GRASS AND STOPPED. R MAIN AND NOSEWHEEL STAYED DOWN AND LOCKED. AT THIS POINT, I PULLED ALL ENG LEVERS AFT, SHUT OFF MASTER AND FUEL, AND EXITED THE ACFT. PUZZLING ELEMENTS -- FIRST, R MAIN SHOWING NOT DOWN AND LOCKED AT SWF. SECOND, L MAIN COLLAPSED AFTER ALL DOWN AND LOCKED INDICATION. TEMP WAS APPROX 20 DEGS F. PERSONALLY SUSPECT GEAR SELECTOR LEVER MALFUNCTION OR STRUT FAILURE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR WAS CALLED TO SEE IF ANYTHING HAD BEEN DETERMINED WHY THE L GEAR COLLAPSED. HE STATED THAT THIS TYPE OF FAILURE HAD HAPPENED BEFORE ON PIPER TWIN ACFT BUT HAD NO DEFINITE FACTS TO BACK UP THAT STATEMENT. ALTHOUGH EXACT CAUSE OF FAILURE HAS NOT BEEN DETERMINED, IT IS SUSPECTED THAT ENG EXHAUST AFFECTS A RUBBER GROMMET THAT HELPS TO ASSURE GEAR IS IN LOCKED POS. ACFT WAS PUT ON JACKS AND GEAR LOWERED. THE GEAR WENT TO LOCKED POS AS IT SHOULD. PROB IS, THE GEAR RETRACTED DURING ROLLOUT AT ABOUT 50-60 KTS. RPTR BELIEVES THE ACFT WILL BE TOTALED AS IT WAS AN OLDER MODEL OF THE NAVAJO. WITH THE GEAR COLLAPSE, THE PROP WAS BENT AND COMPLETE ENG TEARDOWN WILL HAVE TO BE ACCOMPLISHED. THAT WORK ALONE IS ESTIMATED TO BE WORTH MORE THAN MARKET VALUE OF ACFT.

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.