Narrative:

Prior to landing the gear was verified down and locked just before glideslope intercept and at 1;000 AGL during a 'gumps' check. All three gear position indicator lights were green and the nose gear was visually checked in a mirror on the starboard engine nacelle. After touching down; normal breaking effort was used and the aircraft was allowed to coast to the next exit. During the roll out a vibration was noted similar to a nose wheel shimmy or flat main tire; it was determined by the crew that the nose wheel had gone flat. I contacted the tower while we were still rolling out on the runway of the problem and requested assistance. The tower asked if we would be able to make to our exit and I replied that we would try; as we were completing the turn onto our exit. While looking out the side window for the hold short line I noticed the engine nacelle looked oddly close to the ground and seemed to be trending to getting even closer. I immediately pulled the mixture controls and reached for the fuel shut off valves; the pilot flying (also an meii) had just gotten the fuel valves and was shutting off the fuel pumps and magnetos. Despite the immediate action the props struck the ground while they were winding down. What was odd about the collapse was the rate it occurred at. I estimate it took about 3 seconds; as if it retracted and not collapsed? Maybe the hydraulic system was fighting the collapse?the factors as I see them start during preflight. We checked the gear limit switches on all three landing gear and the down locks on the main landing gear but I did not check the nose gear down locks (I didn't ask the other 2 pilots if they checked the nose wheel lock). None of us are a&P's but inspecting the damage later it looked like the stud the hydraulic lock engages was bent and not properly locked. Maybe it was preexisting or a result of the collapse; now we don't know. The decision to clear the runway instead of stopping where we were bothers me in hindsight. Due to recent snow there was only one available runway to the airport; we knew this when the tower asked us if we would be able to clear the runway and wanted to get off the runway so we wouldn't close the airport (which we did anyway!) we let external pressures and previous experience with flat tires influence our decision making. The transition between the runway and taxiway hold short line was covered in jagged ice about 1-2 inches deep; I believe that under normal conditions taxing over the ice would have been fine; but with the flat nose wheel the resistance was too much for the hydraulic and over center locks even with idle power and full aft elevator. I am interested to see if it was a mechanical failure due to defects in the design and/or parts that caused the accident or simply mishandling on our part. In the future the hydraulic down lock on the nose wheel must be better understood and inspected before flight and one must never attempt to taxi any distance in a seminole with a flat nose tire.

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Original NASA ASRS Text

Title: While attempting to clear the runway with a flat tire; a PA44 instructor pilot experienced a nose gear collapse.

Narrative: Prior to landing the gear was verified down and locked just before glideslope intercept and at 1;000 AGL during a 'GUMPS' check. All three gear position indicator lights were green and the nose gear was visually checked in a mirror on the starboard engine nacelle. After touching down; normal breaking effort was used and the aircraft was allowed to coast to the next exit. During the roll out a vibration was noted similar to a nose wheel shimmy or flat main tire; it was determined by the crew that the nose wheel had gone flat. I contacted the Tower while we were still rolling out on the runway of the problem and requested assistance. The Tower asked if we would be able to make to our exit and I replied that we would try; as we were completing the turn onto our exit. While looking out the side window for the hold short line I noticed the engine nacelle looked oddly close to the ground and seemed to be trending to getting even closer. I immediately pulled the mixture controls and reached for the fuel shut off valves; the pilot flying (also an MEII) had just gotten the fuel valves and was shutting off the fuel pumps and magnetos. Despite the immediate action the props struck the ground while they were winding down. What was odd about the collapse was the rate it occurred at. I estimate it took about 3 seconds; as if it retracted and not collapsed? Maybe the hydraulic system was fighting the collapse?The factors as I see them start during preflight. We checked the gear limit switches on all three landing gear and the down locks on the main landing gear but I did not check the nose gear down locks (I didn't ask the other 2 pilots if they checked the nose wheel lock). None of us are A&P's but inspecting the damage later it looked like the stud the hydraulic lock engages was bent and not properly locked. Maybe it was preexisting or a result of the collapse; now we don't know. The decision to clear the runway instead of stopping where we were bothers me in hindsight. Due to recent snow there was only one available runway to the airport; we knew this when the Tower asked us if we would be able to clear the runway and wanted to get off the runway so we wouldn't close the airport (which we did anyway!) We let external pressures and previous experience with flat tires influence our decision making. The transition between the runway and taxiway hold short line was covered in jagged ice about 1-2 inches deep; I believe that under normal conditions taxing over the ice would have been fine; but with the flat nose wheel the resistance was too much for the hydraulic and over center locks even with idle power and full aft elevator. I am interested to see if it was a mechanical failure due to defects in the design and/or parts that caused the accident or simply mishandling on our part. In the future the hydraulic down lock on the nose wheel must be better understood and inspected before flight and one must never attempt to taxi any distance in a Seminole with a flat nose tire.

Data retrieved from NASA's ASRS site as of April 2012 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.