Narrative:

I received my work assignment for the night. I was assigned to the nose landing gear removal and replacement on a [B737-300] aircraft with mechanic 'Y' and I waited for the beginning of shift and then for two fellow mechanics to taxi the aircraft to the hangar to begin our tasks. The aircraft arrived and was positioned in the hangar by other mechanics on out crew (there were five other mechanics assigned to this aircraft). Aircraft was a 'hangar queen' as all nose gear change aircraft are and not scheduled out [for a few days] for revenue service.we quickly moved our work table; the gear change cart and our toolboxes to the nose of the aircraft to begin gear removal task. Another mechanic proceeded to fit the nose jack pad to the left side of the fuselage while I entered the nose wheel well to start assessing what needed to be done and look for any extra non-routine items that commonly come up during nose gear changes. I proceeded to start pulling cotter pins from all the bolts that need to be removed. I removed the bolts from the door rods on both sides where they attach to the gear which makes it easier to remove the access panels in the back of the gear well.as I was removing the bolts from the door rods; mechanic 'Y' was starting to jack the nose of the aircraft. I stated that we needed to deflate the nose strut prior to jacking the nose up for gear removal. Mechanic 'Y' proceeded to remove the jack and I grabbed the drain hose and a wrench to deflate the strut. After the strut was completely deflated; I removed the drain tube and told the mechanic 'Y' he could put the jack in position and 'seat' it. I continued to remove the access panels in the back of the gear well. As I was grabbing some tools to remove other components; I noticed fellow mechanic 'Z' starting a conversation with mechanic 'Y'; I paused for a minute or two until a supervisor walked up. He asked what was going on and I stated that mechanic 'Y' and 'Z' were having a discussion. The supervisor then told mechanic 'Z' to leave us alone because we have a job to get done. I then continued to remove the hydraulic lines from the retract actuator; cap them and move them out of the way. Looking down at this point; I saw fellow mechanic 'X' starting to remove the taxi light harness and I also noted a foot of the jack next to the aircraft which I assumed was under the jack pad. (Our hangar floor is very un-level so there is no set spot where the jack is placed. Often; the jack must be rotated to find a spot that will work).I removed the retract actuator; the down-lock springs from their aft most attach points; then proceeded to remove the 'three point bolt' from the apex of the upper and lower drag brace and the lock brace. This bolt is normally free to rotate within the large pin that holds the upper and lower drag braces together so it came out easily. Within about 5-10 seconds of removing the bolt; I heard a loud snap and I was on my knees with the gear collapsed in front of me. It wasn't until I looked down that I noticed I was dripping blood onto one of the tires. I asked for some towels to stop the bleeding because I wasn't yet aware that I was going to be able to crawl out of the wheel well. With some help from my fellow mechanic 'X'; I was able to rotate my body and remove myself from the wheel well. I was placed in a chair and awaited the fire department and ambulance arrival.

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Original NASA ASRS Text

Title: Two mechanics report about a Nose Landing Gear removal on B737-300 aircraft that resulted in the nose gear collapsing on one of the Mechanic's in the wheelwell and narrowly missing another Mechanic removing the taxi light electrical harness at the lower strut.

Narrative: I received my work assignment for the night. I was assigned to the Nose Landing Gear Removal and Replacement on a [B737-300] aircraft with Mechanic 'Y' and I waited for the beginning of shift and then for two fellow mechanics to taxi the aircraft to the hangar to begin our tasks. The aircraft arrived and was positioned in the hangar by other mechanics on out crew (there were five other mechanics assigned to this aircraft). Aircraft was a 'hangar queen' as all nose gear change aircraft are and not scheduled out [for a few days] for revenue service.We quickly moved our work table; the gear change cart and our toolboxes to the nose of the aircraft to begin gear removal task. Another Mechanic proceeded to fit the Nose jack pad to the left side of the fuselage while I entered the nose wheel well to start assessing what needed to be done and look for any extra Non-Routine items that commonly come up during nose gear changes. I proceeded to start pulling cotter pins from all the bolts that need to be removed. I removed the bolts from the door rods on both sides where they attach to the gear which makes it easier to remove the access panels in the back of the gear well.As I was removing the bolts from the door rods; Mechanic 'Y' was starting to jack the nose of the aircraft. I stated that we needed to deflate the Nose strut prior to jacking the nose up for gear removal. Mechanic 'Y' proceeded to remove the jack and I grabbed the drain hose and a wrench to deflate the strut. After the strut was completely deflated; I removed the drain tube and told the Mechanic 'Y' he could put the jack in position and 'seat' it. I continued to remove the access panels in the back of the gear well. As I was grabbing some tools to remove other components; I noticed fellow Mechanic 'Z' starting a conversation with Mechanic 'Y'; I paused for a minute or two until a Supervisor walked up. He asked what was going on and I stated that Mechanic 'Y' and 'Z' were having a discussion. The Supervisor then told Mechanic 'Z' to leave us alone because we have a job to get done. I then continued to remove the hydraulic lines from the Retract Actuator; cap them and move them out of the way. Looking down at this point; I saw fellow Mechanic 'X' starting to remove the taxi light harness and I also noted a foot of the jack next to the aircraft which I assumed was under the jack pad. (Our hangar floor is very un-level so there is no set spot where the jack is placed. Often; the jack must be rotated to find a spot that will work).I removed the Retract Actuator; the Down-Lock Springs from their aft most attach points; then proceeded to remove the 'three point bolt' from the Apex of the upper and lower drag brace and the lock brace. This bolt is normally free to rotate within the large pin that holds the upper and lower drag braces together so it came out easily. Within about 5-10 seconds of removing the bolt; I heard a loud snap and I was on my knees with the gear collapsed in front of me. It wasn't until I looked down that I noticed I was dripping blood onto one of the tires. I asked for some towels to stop the bleeding because I wasn't yet aware that I was going to be able to crawl out of the wheel well. With some help from my fellow Mechanic 'X'; I was able to rotate my body and remove myself from the wheel well. I was placed in a chair and awaited the Fire Department and ambulance arrival.

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.