Air carrier technician reported upon starting the right engine they heard a loud bang and immediately shut down the engine. They inspected the engine and found the technician's hammer in the inlet which caused considerable damage to the fan blades and fan case.
Synopsis
Air carrier technician reported upon starting the right engine they heard a loud bang and immediately shut down the engine. They inspected the engine and found the technician's hammer in the inlet which caused considerable damage to the fan blades and fan case.
Narrative
At around XA00 on Day 0; I and my colleague boarded aircraft X in the ZZZ maintenance hangar in order to take the plane to the sound wall for engine runs following maintenance. Upon starting the RH engine; a loud bang was heard and the aircraft shuddered. We stopped the engine and talked to the lead techs who had heard the sound and immediately come over to investigate. Upon looking into the inlet; they found the remains of my coworker's hammer that had been left there; which severely damaged all the fan blades; the fan case and inlet. We shut the APU down and tugged the plane back into the hangar to assess the damage while several other mechanics were asked to walk the ramp to collect any additional FOD created by the incident.The core failure that led to the incident was lack of a proper walkaround before taking the plane outside to run. The plane had been in the hangar all night and we had been all over it inside and outside for a bi-weekly inspection; so I got complacent in assuming we knew everything we needed to know about the plane and I should focus on known sources of aircraft damage such as ground equipment and ladders; unsecured doors; safety harness ropes getting caught in the flight controls; etc... But there is no 'hangar version' of the run-taxi walkaround. Our training tells us how and why the walkaround inspection is supposed to be done. If I'd done the proper procedure all of those things would have been caught anyway; and the hammer would certainly have been found before any damage occurred.
Second reporter narrative
On Day 0 at approximately around XB45 (mech )and myself were starting engine 2 on aircraft X. (Mech) was sitting left seat and I was sitting right seat. While the engine was coming up to idle there was a loud bang followed by a severe shutter. I immediately turned off engine 2 while coasting down I monitored the engine for any more issues of which there were none. Soon thereafter multiple mechanics came outside to see what the noise was. Upon inspection there was a hammer found in the inlet that caused considerable visible damage. The hammer was mine and I take full reasonability for putting the hammer it in the inlet and forgetting about it. The reason I put the hammer in the inlet was to stop the fan from wind milling while working on the engine. The fan blades were wind milling at a high speed due a shop fan that I positioned behind the engine to cool down the engine to be able to work on it. After completing my work and putting away my tools I did not perform a proper toolbox inventory nor did I check my immediate area for any loose items. Prior to taking the aircraft out of the hangar I was moving equipment around so it could be taken outside but I did not perform a proper walkaround prior to getting on the aircraft. All of these aforementioned actions after completing my work are a deviation from my normal routines and I have no good reason for this. I did clear engine 2 prior to start but I did not see the hammer most likely due to it being dark as well as its position in the inlet. Perform an aircraft walk around before Run/taxi actions at all times. Document when non-standard maintenance routines are used. Use Run/Taxi checklist. Crosscheck performed by both mechanics and a leadership. Use high visibility streamers when there is a chance that tooling may be left on an aircraft
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.