Date: 201202
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: MBB-BK 117 All Series
Operator: Air Taxi
Operating under: Part 135
Mission: Ambulance
Flight phase: Parked
Aircraft component: Electrical/Electronic Panel & Parts
Reporter organization: Air Taxi
Reporter function: Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Situational Awareness; Fatigue; Distraction; Confusion; Time Pressure; Workload; Troubleshooting
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: In-flight
Result: Flight Crew Landed As Precaution; General Maintenance Action
Contributing factors: Incorrect / Not Installed / Unavailable Part; Equipment / Tooling; Environment - Non Weather Related; Company Policy; Aircraft; Human Factors; Procedure; Manuals; Logbook Entry
Primary problem: Human Factors

Narrative: We had been working 80+ hours a week for two weeks prior to the event. I also had 60+ hours the two weeks prior to that. My [Operations] Base had been taken out by a tornado that went through ZZZ; which has left everything in disarray. I have been working on spare helicopters as our primary helicopter since I was hired three months ago. I have not had a helicopter that has been in good working order until Aircraft X; a BK-117 helicopter arrived. We have been feverishly working on Aircraft Y for over a month; to try to figure out all the wiring and electrical problems [found while] troubleshooting a Medical Power Inverter and [electrical] outlets. We found extensive wiring damage that required major disassembly of Aircraft Y to fix. We then discovered that the wiring did not match the Wiring Diagram; so we had to re-wire back to original configuration. All systems were checking 'good' on the Ground Checks and there was pressure to get Aircraft Y back in service so the other aircraft could be flown to ZZZ1 for training.When Aircraft Y was brought back to the pad; the medical crew wanted to test the electrical system to make sure it was going to hold up and it immediately failed. We began troubleshooting which meant we had to remove the access panel. We decided to remove the inverter and install the old inverter to see if that fixed the problem; and it did; that night. The next morning the medical crew wanted to run it again; because they were told they would have one week to make sure it was going to be reliable. They plugged everything in again and it immediately failed again. We were in the process of troubleshooting the problem when the decision was made to take the aircraft with the bad Medical Inverter System to ZZZ1 for training. I was then told to get Aircraft Y ready to go. We were then told to swap back into Aircraft X; because we were going to put it back in service. At that point I needed to catch up on all the maintenance tracking program paperwork and clear some MEL paperwork; then do the aircraft Spare Transfer Log; and make sure that everything that was supposed to be with that aircraft was in it and accounted for. The pilot started loading the boxes of logbooks and General Operations Manuals (GOM) and Flight Manuals for [Aircraft Y] before I had gone through them; so I started going through them to make sure they were accounted for. In all of the rush to get all the paperwork done and stuff loaded and ready to go; I forgot about putting the access panel back on. The pilot did his pre-flight and did not say anything so I figured everything was OK. Aircraft had left base when I was in the office doing paperwork and I turned around and noticed the panel sitting there; I immediately notified my Supervisor and the Duty Pilot. The Duty Pilot called ZZZ2 to notify the pilot of the Aircraft Y and have him call back. The pilot of the aircraft then notified his Supervisor who in turn grounded Aircraft Y until the access panel was put back on. I then drove 200 miles to ZZZ3 to install the panel back on Aircraft Y and by that time the weather had made it impossible to continue the flight that day. Aircraft Y was hangared and I drove back to ZZZ to hangar my other aircraft.I then drove back to ZZZ3 to pull Aircraft Y out of the hangar; to be ready to launch when the weather permitted. I then drove back to ZZZ to check on my primary aircraft. By this time it was daybreak and I was dead tired and starting to get sick; which is why it has taken me this long to submit this report. The possibility of incoming bad weather was also a factor in all of this. The workload of Aircraft Y; along with the rush to get it in service; and then the numerous changes of plans at the last minute was the biggest factors involved. Suggest that if an aircraft needs the amount of work that Aircraft Y needs; it should go to a FAR 145 Repair Station to be worked until it is in correct working order. It should not be dumped on the Base Mechanic to basically refurbish an aircraft in the field; while taking care of another aircraft at the same time. There should be better planning involved in situations like this. Furthermore the technicians working on spare aircraft should treat any spare as if it were their personal aircraft; not neglect it like the two aircraft that I have had previous to Aircraft X. Aircraft Y and Z were both neglected and it showed up while it was here. Aircraft should not be assigned a mission until it is flight ready and mission capable.




Synopsis: A Helicopter Mechanic has a work environment that included high workload saturation; excessive work hours; fatigue. A Medical Power Inverter access panel was not reinstalled on a BK-117 air ambulance helicopter and the Maintenance Base was in disarray after a tornado struck.