Narrative:

During a removal and installation of a 70/90 seater APU; we had dropped the APU to the floor so it could be loaded onto a shipping crate. We started to lift assembly up to a height that we could place the unit onto the skid when; with out any notice to us; the unit completely did a 180 degree flip and the exhaust nozzle made contact to the hangar floor causing damage to the unit. I did notice that this assembly; while it was being lowered; to be some what unstable but never thought it would do a flip. Later that day while talking to mr. X; he had had the same problem and was hurt and needed medical care as to his injury to his hand. He stated that this has happened several times before. The assembly which the APU is attached to so it can be lifted in place; has what I would have to say is cg critical. Supervisors were notified of problem and no other damage to persons or property was done. If the APU would have done this while it was just being removed or installed and someone would have tried to stop it could have hurt someone else like it did mr. X. We need to take a look at this set up and see if we could maybe make it more stable. Also; if this information would have been passed down to others we may have been able to stop the action and saved the unit from further damage and maybe prevent an injury to the mechanics. 1) the platform; to which the APU is attached; has four turn buckles so it can be adjusted forward or aft which when adjusting might be the cause of the cg problem. This really is the most problematic to the cause of the problem. 2) we may need to make another cable to attach the APU to the hand crank assembly that is attached to the airframe. Since this is not the first time for this maybe we need to talk to the folks that made this assembly to be used to remove and replace APU's.callback conversation with reporter revealed the following information: reporter stated the APU is located in the aft end of the crj-700 fuselage. Access to the APU is through double bay clam shell type doors. The standard procedure in the aircraft maintenance manual (amm); to remove and replace the APU requires three people. Two cable type straps are installed; one on the left side of the APU and one on the right. The amm doesn't indicate this is a center of gravity (cg) critical procedure. Reporter stated he believes another cable strap should be added for the third person to use as a balancing guide; instead of the third mechanic using his hands to balance the APU and prevent it from rotating forward or rotating aft; or flipping over.

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Original NASA ASRS Text

Title: A Mechanic reports there is inadequate information in the Aircraft Maintenance Manual (AMM) and lack of necessary equipment to remove and install the APU on their CRJ-700. Mechanics have been injured and the APU's damaged from flipping over during the procedure.

Narrative: During a removal and installation of a 70/90 seater APU; we had dropped the APU to the floor so it could be loaded onto a shipping crate. We started to lift assembly up to a height that we could place the unit onto the skid when; with out any notice to us; the unit completely did a 180 degree flip and the exhaust nozzle made contact to the hangar floor causing damage to the unit. I did notice that this assembly; while it was being lowered; to be some what unstable but never thought it would do a flip. Later that day while talking to Mr. X; he had had the same problem and was hurt and needed medical care as to his injury to his hand. He stated that this has happened several times before. The assembly which the APU is attached to so it can be lifted in place; has what I would have to say is CG critical. Supervisors were notified of problem and no other damage to persons or property was done. If the APU would have done this while it was just being removed or installed and someone would have tried to stop it could have hurt someone else like it did Mr. X. We need to take a look at this set up and see if we could maybe make it more stable. Also; if this information would have been passed down to others we may have been able to stop the action and saved the unit from further damage and maybe prevent an injury to the mechanics. 1) The platform; to which the APU is attached; has four turn buckles so it can be adjusted forward or aft which when adjusting might be the cause of the CG problem. This really is the most problematic to the cause of the problem. 2) We may need to make another cable to attach the APU to the hand crank assembly that is attached to the airframe. Since this is not the first time for this maybe we need to talk to the folks that made this assembly to be used to remove and replace APU's.Callback Conversation with Reporter revealed the following information: Reporter stated the APU is located in the aft end of the CRJ-700 fuselage. Access to the APU is through double bay clam shell type doors. The standard procedure in the Aircraft Maintenance Manual (AMM); to remove and replace the APU requires three people. Two cable type straps are installed; one on the left side of the APU and one on the right. The AMM doesn't indicate this is a center of gravity (CG) critical procedure. Reporter stated he believes another cable strap should be added for the third person to use as a balancing guide; instead of the third mechanic using his hands to balance the APU and prevent it from rotating forward or rotating aft; or flipping over.

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.