Narrative:

I was instructed to perform a rigging check of the main rotor controls. The servo input rods were previously disconnected from the main rotor servo input levers because of other maintenance performed. I performed the rigging as instructed and found everything within limits. No adjustments were necessary. Upon completion of the rigging; I proceeded in installing the input rods on to the main rotor servos. At that time; I received the bag of hardware that contained the original hardware stack up; including 2 'diaper' safety pins. I question the safety pins at that time; being there was only 2 pins and 3 bolts. [Another technician] informed me that the right and left aft servos were pinned originally; and the forward was cotter pinned. I did not think; at the time; there was anything wrong with using safety pins in place of cotter pins on the main rotor servos. I have seen this many times before on various helicopters; including AS350's. I then inspected the hardware and pins; and found nothing wrong with them; so I proceeded to install the bolts in accordance with the appropriate maintenance manual reference and contacted the aircraft quality assurance inspector for an 'ok to close' for the plastic ice shields installed over the input rod levers. At that time [the quality assurance inspector] questioned why there were only two safety pins; and one cotter pin. I replied that is how it was originally; and that I had seen safety pins in that position previously. He agreed; so I continued; and installed the ice covers.I believe complacency; a lack of attention to detail; and a lack of training were the main causes of this event. I never questioned the use of safety pins there because I had seen them multiple times in that location. Upon research I found a standard practices reference in the AS350 spm that noted the use of safety pins in the main gearbox suspension bars; and in cowling latches. As well as their use in 'plain pins'. However; I could not find any reference to using them in place of cotter pins on bolts. I think this is a common mistake; and the cause of them being installed in this location on other aircraft. Making me complacent; because of my previous experience; and the mentality of 'that's how it came in'.

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Original NASA ASRS Text

Title: Mechanic reported failing to verify that the cotter pin in the nuts when inspecting the main servo flight control input rods on a Eurocopter AS350. One of the nuts was safetied with a cotter pin and the other was safetied with diaper pins.

Narrative: I was instructed to perform a rigging check of the Main Rotor Controls. The Servo Input rods were previously disconnected from the Main Rotor Servo Input levers because of other maintenance performed. I performed the rigging as instructed and found everything within limits. No adjustments were necessary. Upon completion of the rigging; I proceeded in installing the Input Rods on to the Main Rotor Servos. At that time; I received the bag of hardware that contained the original hardware stack up; including 2 'diaper' safety pins. I question the safety pins at that time; being there was only 2 pins and 3 bolts. [Another technician] informed me that the Right and Left Aft servos were pinned originally; and the forward was cotter pinned. I did not think; at the time; there was anything wrong with using safety pins in place of cotter pins on the Main Rotor Servos. I have seen this many times before on various helicopters; including AS350's. I then inspected the hardware and pins; and found nothing wrong with them; so I proceeded to install the bolts in accordance with the appropriate maintenance manual reference and contacted the aircraft Quality Assurance inspector for an 'OK to close' for the plastic ice shields installed over the Input Rod Levers. At that time [the Quality Assurance inspector] questioned why there were only two safety pins; and one cotter pin. I replied that is how it was originally; and that I had seen safety pins in that position previously. He agreed; so I continued; and installed the Ice Covers.I believe complacency; a lack of attention to detail; and a lack of training were the main causes of this event. I never questioned the use of safety pins there because I had seen them multiple times in that location. Upon research I found a standard practices reference in the AS350 SPM that noted the use of safety pins in the Main Gearbox Suspension bars; and in cowling latches. As well as their use in 'plain pins'. However; I could not find any reference to using them in place of cotter pins on bolts. I think this is a common mistake; and the cause of them being installed in this location on other aircraft. Making me complacent; because of my previous experience; and the mentality of 'that's how it came in'.

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.