Home-built small aircraft suffers main landing gear assembly failure.

Attributes
ACN	128125
Time
Date	198911
Day	Mon
Place
Locale Reference	airport : apc
State Reference	CA
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	general aviation : personal
Make Model Name	Small Aircraft
Flight Phase	descent : approach landing other
Flight Plan	None
Person 1
Affiliation	Other
Function	observation : observer
Qualification	pilot : cfi pilot : instrument pilot : commercial
Experience	flight time last 90 days : 75 flight time total : 800 flight time type : 35
ASRS Report	128125
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Events
Anomaly	aircraft equipment problem : critical inflight encounter other other anomaly other other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Consequence	other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

I was returning to napa airport, as a passenger, with a pilot who was my former student. The tower had cleared us for a downwind entry. When my friend approached the runway. He determined that the visibility (from his perspective) was unsafe, and he added power and set up for another approach. Visibility is very critical for the landing phase in this airplane because of the blind areas forward of the pilot, and because of the bi-wing design. Also, good directional control on landing is very important due to the relatively high approach speeds (90 mph). On the second attempt to land, the pilot touched down, but did not like the ambient runway lighting and went around for a second time. I then radioed the tower and asked if the light intensity could be increased. The tower told me that they were at full intensity, however we could turn up the approach lights for runway 36 if we wanted to land on that runway. Because of the increased safety of the brighter runway environment and relatively slight crosswind component, the decision was made by the pilot to land on runway 36. A normal approach was made, and he made a very fine T/D; however, during the rollout, the airplane began to turn to the right, just prior to the final brake application to complete the landing. The pilot applied left rudder and differential braking to counter this uncontrolled right turn, but was unsuccessful. The airplane finally stopped approximately 90 degrees to the runway centerline. I thought a tire had blown, and radioed the tower for assistance in getting the airplane off the runway. When we climbed out, we saw that the main gear structure had failed. The main assembly had somehow separated internally and widened out, allowing the whole fuselage to drop to within inches from the ground. I have subsequently learned that this same problem has occurred to several other pilots flying the same model of airplane.

Original NASA ASRS Text

Title: HOME-BUILT SMA SUFFERS MAIN LNDG GEAR ASSEMBLY FAILURE.

Narrative: I WAS RETURNING TO NAPA ARPT, AS A PAX, WITH A PLT WHO WAS MY FORMER STUDENT. THE TWR HAD CLRED US FOR A DOWNWIND ENTRY. WHEN MY FRIEND APCHED THE RWY. HE DETERMINED THAT THE VISIBILITY (FROM HIS PERSPECTIVE) WAS UNSAFE, AND HE ADDED PWR AND SET UP FOR ANOTHER APCH. VISIBILITY IS VERY CRITICAL FOR THE LNDG PHASE IN THIS AIRPLANE BECAUSE OF THE BLIND AREAS FORWARD OF THE PLT, AND BECAUSE OF THE BI-WING DESIGN. ALSO, GOOD DIRECTIONAL CONTROL ON LNDG IS VERY IMPORTANT DUE TO THE RELATIVELY HIGH APCH SPDS (90 MPH). ON THE SECOND ATTEMPT TO LAND, THE PLT TOUCHED DOWN, BUT DID NOT LIKE THE AMBIENT RWY LIGHTING AND WENT AROUND FOR A SECOND TIME. I THEN RADIOED THE TWR AND ASKED IF THE LIGHT INTENSITY COULD BE INCREASED. THE TWR TOLD ME THAT THEY WERE AT FULL INTENSITY, HOWEVER WE COULD TURN UP THE APCH LIGHTS FOR RWY 36 IF WE WANTED TO LAND ON THAT RWY. BECAUSE OF THE INCREASED SAFETY OF THE BRIGHTER RWY ENVIRONMENT AND RELATIVELY SLIGHT XWIND COMPONENT, THE DECISION WAS MADE BY THE PLT TO LAND ON RWY 36. A NORMAL APCH WAS MADE, AND HE MADE A VERY FINE T/D; HOWEVER, DURING THE ROLLOUT, THE AIRPLANE BEGAN TO TURN TO THE RIGHT, JUST PRIOR TO THE FINAL BRAKE APPLICATION TO COMPLETE THE LNDG. THE PLT APPLIED LEFT RUDDER AND DIFFERENTIAL BRAKING TO COUNTER THIS UNCONTROLLED RIGHT TURN, BUT WAS UNSUCCESSFUL. THE AIRPLANE FINALLY STOPPED APPROX 90 DEGS TO THE RWY CENTERLINE. I THOUGHT A TIRE HAD BLOWN, AND RADIOED THE TWR FOR ASSISTANCE IN GETTING THE AIRPLANE OFF THE RWY. WHEN WE CLBED OUT, WE SAW THAT THE MAIN GEAR STRUCTURE HAD FAILED. THE MAIN ASSEMBLY HAD SOMEHOW SEPARATED INTERNALLY AND WIDENED OUT, ALLOWING THE WHOLE FUSELAGE TO DROP TO WITHIN INCHES FROM THE GND. I HAVE SUBSEQUENTLY LEARNED THAT THIS SAME PROB HAS OCCURRED TO SEVERAL OTHER PLTS FLYING THE SAME MODEL OF AIRPLANE.

Data retrieved from NASA's ASRS site as of August 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.