Narrative:

The original discrepancy was # 1 engine overspeed and shut down on approach to roof top helipad of hospital. Upon landing; pilot X; the on-duty pilot; called our lead mechanic (lead mechanic X). He informed lead mechanic X of what had occurred. Lead mechanic X called me early evening and informed me to gather tools and head toward the hospital. During travel; I was in touch with lead X who informed me that he was in contact with our regional manager. Lead X briefed me prior to arrival of what he and the regional manager came up with for me to begin trouble shooting engine shut down cause. Upon arrival; I met and was briefed by pilot X as to what had transpired. I proceeded to complete task that was relayed to me. I performed a complete visual check of engine and airframe with no defects noted. I notified lead X and was told to have pilot X start # 1 engine and to monitor the engine indications for erratic indications of abnormalities. After engine start; there were no issues. I proceeded to do power check; beep checks and engine overspeed checks with no faults or discrepancies. After runs; I was able to get someone in the hospital to log me onto a computer and I researched in the bk-117 maintenance manual (M/M) engine overspeed inspection and found that there was no inspection listed. I was then told to finish with that for the night and that lead mechanic X and the regional manager were going to call the honeywell engine technical representative the next morning. The next morning I contacted lead X and he told me he was in contact with technical representative and that the representative would get back on how to proceed. Approximately mid-day; I was told to report back to the hospital and meet up with lead mechanic X. I diverted to our company base 145 repair station ZZZ1 and acquired an engine governor and fuel control that I was told is what the technical representative wanted us to inspect/change. When I arrived; lead X was in the process of removing the governor per the technical representative. Lead X then installed the governor I had brought. We then leaked check the engine air system and reinstalled the cowl to prepare for engine run. Lead mechanic X and pilot X ran the aircraft and performed beep checks which were found to be within limits. Lead X was then in contact with the regional manager and the engine manufacturer technical representative. The final word was sign-off the work that was performed and release the aircraft back to ZZZ airport; due to weather inbound and the fact that we had scheduled inspections that we were planning on doing the next day in the hangar under weather. The aircraft was flown to ZZZ1 for refuel where we informed pilot X to wait for my arrival. I arrived at ZZZ1 repair station did a visual check of the # 1 engine; no discrepancies noted. Pilot X then returned back to ZZZ airport and put the ship in the hangar. The next morning; lead mechanic X and I arrived and began to do the scheduled inspection. Throughout the day lead X was fielding calls about what had happened and I was researching answers to the questions. While researching; I found in the honeywell lts 101-B engine maintenance manual (M/M) an inspection checklist for engine overspeed. I informed lead X and we reviewed the checklist and found out that the engine required topping and a dye penetrant (pen) inspection of the turbine wheel; all of which had not completed before I returned the aircraft to service the prior evening. We relayed the info to the regional manager. After more research and calls to technical representatives; we found out that the dye pen inspection [procedure] results in an engine change due to the level of dye penetrant required by the manual. We have ordered the parts to change the engine. When we informed the regional manager what had happened; he told us to complete this form. [Recommend] we receive better back support from the regional manager or aircraft maintenance manual (amm) when inareas that have limited; to no internet access. I should have slowed down and asked more questions about what was researched instead of taking for granted that all other parties involved had already made sure I was covered; in the maintenance I was told to perform. In hindsight; I should have pushed the issue of limited; to no internet access and made sure someone had researched the engine manual; as I had already researched the airframe manual myself. Flight canceled. While reading manuals the next day at maintenance hangar for the root cause of engine shut down; due to no internet at hospital helipad; found checklist for overspeed.

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Original NASA ASRS Text

Title: Two Aircraft Maintenance Technicians (AMTs) describe factors that contributed to their not accomplishing an Overspeed Checklist after a BK-117 Eurocopter pilot reported the indicator needles on #1 Engine had gone 'Sky-high.' The Honeywell LTS 101-B Engine had shut down inflight; approximately 200 FT above a hospital helipad.

Narrative: The original discrepancy was # 1 Engine overspeed and shut down on approach to roof top helipad of hospital. Upon landing; Pilot X; the on-duty pilot; called our Lead Mechanic (Lead Mechanic X). He informed Lead Mechanic X of what had occurred. Lead Mechanic X called me early evening and informed me to gather tools and head toward the hospital. During travel; I was in touch with Lead X who informed me that he was in contact with our Regional Manager. Lead X briefed me prior to arrival of what he and the Regional Manager came up with for me to begin trouble shooting engine shut down cause. Upon arrival; I met and was briefed by Pilot X as to what had transpired. I proceeded to complete task that was relayed to me. I performed a complete Visual Check of Engine and Airframe with no defects noted. I notified Lead X and was told to have Pilot X start # 1 Engine and to monitor the engine indications for erratic indications of abnormalities. After engine start; there were no issues. I proceeded to do Power Check; Beep Checks and Engine Overspeed Checks with no faults or discrepancies. After runs; I was able to get someone in the hospital to log me onto a computer and I researched in the BK-117 Maintenance Manual (M/M) Engine Overspeed Inspection and found that there was no inspection listed. I was then told to finish with that for the night and that Lead Mechanic X and the Regional Manager were going to call the Honeywell Engine Technical Representative the next morning. The next morning I contacted Lead X and he told me he was in contact with Technical Representative and that the Representative would get back on how to proceed. Approximately mid-day; I was told to report back to the hospital and meet up with Lead Mechanic X. I diverted to our Company Base 145 Repair Station ZZZ1 and acquired an engine governor and fuel control that I was told is what the Technical Representative wanted us to inspect/change. When I arrived; Lead X was in the process of removing the governor per the Technical Representative. Lead X then installed the governor I had brought. We then leaked check the Engine Air System and reinstalled the cowl to prepare for engine run. Lead Mechanic X and Pilot X ran the aircraft and performed Beep Checks which were found to be within limits. Lead X was then in contact with the Regional Manager and the Engine Manufacturer Technical Representative. The final word was sign-off the work that was performed and release the aircraft back to ZZZ airport; due to weather inbound and the fact that we had scheduled inspections that we were planning on doing the next day in the hangar under weather. The aircraft was flown to ZZZ1 for refuel where we informed Pilot X to wait for my arrival. I arrived at ZZZ1 Repair Station did a Visual Check of the # 1 Engine; no discrepancies noted. Pilot X then returned back to ZZZ Airport and put the ship in the hangar. The next morning; Lead Mechanic X and I arrived and began to do the scheduled inspection. Throughout the day Lead X was fielding calls about what had happened and I was researching answers to the questions. While researching; I found in the Honeywell LTS 101-B Engine Maintenance Manual (M/M) an Inspection Checklist for Engine Overspeed. I informed Lead X and we reviewed the checklist and found out that the engine required Topping and a Dye Penetrant (Pen) Inspection of the turbine wheel; all of which had not completed before I returned the aircraft to service the prior evening. We relayed the info to the Regional Manager. After more research and calls to technical representatives; we found out that the Dye Pen Inspection [procedure] results in an engine change due to the level of dye penetrant required by the Manual. We have ordered the parts to change the engine. When we informed the Regional Manager what had happened; he told us to complete this form. [Recommend] we receive better back support from the Regional Manager or Aircraft Maintenance Manual (AMM) when inareas that have limited; to no internet access. I should have slowed down and asked more questions about what was researched instead of taking for granted that all other parties involved had already made sure I was covered; in the maintenance I was told to perform. In hindsight; I should have pushed the issue of limited; to no internet access and made sure someone had researched the Engine Manual; as I had already researched the Airframe Manual myself. Flight canceled. While reading manuals the next day at maintenance hangar for the root cause of engine shut down; due to no internet at hospital helipad; found checklist for overspeed.

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.