Narrative:

[I (the CFI)] was conducting complex airplane flight instruction to a private pilot with a passenger in the rear seat. The private pilot requested that a demonstration of a landing be performed on an improved sod runway. The airplane initially landed on the paved runway and came to a full stop. The CFI exited the airplane and walked several hundred feet of the improved sod runway to verify condition of the strip was suitable. After determining that the improved sod runway was suitable for landing; the CFI referenced performance charts for the airplane and determined that the runway was of suitable length to make a landing should a touch and go procedure need to be aborted. The CFI reentered the airplane and communicated the condition of the strip as well as his intention to demonstrate a touch and go on the sod runway to the private pilot. The airplane departed the paved runway and entered left traffic. On the left downwind; and prior to turning base leg; the gear lever was placed into the down position and a gumps check was conducted. On final; directly before touchdown of the main gear; the private pilot verbally indicated for a second time that the gear was indicating to be down and locked by saying 'green lights.'immediately upon touchdown of the main gear; the left main gear collapsed; the left wing contacted the runway; and the nose gear subsequently collapsed. The airplane veered to the left and came to a stop on the runway edge approximately 600 feet from the threshold. No injuries were sustained and there was no further damage to property other than the damaged airplane.all parties involved agree that nothing abnormal was observed during the approach or the landing leading up to the collapsed gear. There was not a crosswind present at the time of the approach or the landing and no gusts or wind shear were encountered. There was no indication of an abnormally harsh touch down or a landing that would have led to side loading of the left main gear. This was both observable to the CFI; the private pilot; and was confirmed by the touchdown marks left on the runway surface. The marks at the touch down point were superficial leading to the observation that the gear did not strike hard and neither of the main gear wheels had dug into the turf. There was no nose gear mark before or near the main gear marks that would indicate that the nose wheel had been struck first or that the airplane had been landed flat. The CFI perceived what he recalled to be a hollow snapping noise immediately after the main gears touched the runway and the collapsing of the gear seemed to happen simultaneously with this abnormal event.the CFI and private pilot drew the conclusion that a structural failure of the left main gear must have occurred upon touchdown of the left main wheel and that this mechanical failure resulted in the subsequent failure of the nose gear.

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Original NASA ASRS Text

Title: PA28 flight instructor reported the left landing gear collapsed during landing on an improved sod runway.

Narrative: [I (the CFI)] was conducting complex airplane flight instruction to a private pilot with a passenger in the rear seat. The private pilot requested that a demonstration of a landing be performed on an improved sod runway. The airplane initially landed on the paved runway and came to a full stop. The CFI exited the airplane and walked several hundred feet of the improved sod runway to verify condition of the strip was suitable. After determining that the improved sod runway was suitable for landing; the CFI referenced performance charts for the airplane and determined that the runway was of suitable length to make a landing should a touch and go procedure need to be aborted. The CFI reentered the airplane and communicated the condition of the strip as well as his intention to demonstrate a touch and go on the sod runway to the private pilot. The airplane departed the paved runway and entered left traffic. On the left downwind; and prior to turning base leg; the gear lever was placed into the down position and a GUMPS check was conducted. On final; directly before touchdown of the main gear; the private pilot verbally indicated for a second time that the gear was indicating to be down and locked by saying 'green lights.'Immediately upon touchdown of the main gear; the left main gear collapsed; the left wing contacted the runway; and the nose gear subsequently collapsed. The airplane veered to the left and came to a stop on the runway edge approximately 600 feet from the threshold. No injuries were sustained and there was no further damage to property other than the damaged airplane.All parties involved agree that nothing abnormal was observed during the approach or the landing leading up to the collapsed gear. There was not a crosswind present at the time of the approach or the landing and no gusts or wind shear were encountered. There was no indication of an abnormally harsh touch down or a landing that would have led to side loading of the left main gear. This was both observable to the CFI; the private pilot; and was confirmed by the touchdown marks left on the runway surface. The marks at the touch down point were superficial leading to the observation that the gear did not strike hard and neither of the main gear wheels had dug into the turf. There was no nose gear mark before or near the main gear marks that would indicate that the nose wheel had been struck first or that the airplane had been landed flat. The CFI perceived what he recalled to be a hollow snapping noise immediately after the main gears touched the runway and the collapsing of the gear seemed to happen simultaneously with this abnormal event.The CFI and private pilot drew the conclusion that a structural failure of the left main gear must have occurred upon touchdown of the left main wheel and that this mechanical failure resulted in the subsequent failure of the nose gear.

Data retrieved from NASA's ASRS site 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.