EC135
Maintenance Airframe; Maintenance Inspection Authority; Maintenance Powerplant
Maintenance Technician 23
Troubleshooting; Fatigue; Time Pressure
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance
General Flight Cancelled / Delayed; General Maintenance Action
Aircraft; Human Factors; Manuals; Procedure
Below is a lengthy statement that I sent to my Director of Maintenance after an incident on [an] aircraft operated by [the Company]. [The Company] has the contract for the [Air Medical Service] Program in [the] surrounding areas. This incident occurred at one of the outlying bases. In synopsis; the event revolved around a pilot finding a Mast Moment Exceedance when he attempted to start the aircraft early in the morning. It details the troubleshooting and corrective actions taken. Actions that later we're deemed inadequate and the Mechanic was fired for allowing the aircraft to go back in service. The primary reason for the termination was 'falsification of records' although I admitted these were typographical errors of omission and not intentionally false. Fatigue was a major factor as well as lack of resources. I had worked 28 hours of overtime during the pay period covering this event. I had 3 hours of sleep before being awoken to go out [and] troubleshoot an aircraft.XA:04; the duty pilot for [Air Medical Service Base 2] calls me and states he had attempted a flight with aircraft. During boot up of the CDS (Cockpit Display System) a '#1 ENG CHIP DETECTOR CT' light had stayed on and an 'INPUT FAIL' message was now on the CDS. It was a particularly humid night and I suggested [to] try a reboot and that I would be on my way to his location. XA:11; [the pilot] calls me back and states the CT light has gone away but now a solid red square and MMEXC0061 is showing on the CDS. I state I will be there shortly. XA:19; I call the on-duty Maintenance Controller while enroute to the site and advise him Aircraft X is out of service. XA:21; I arrive at the [Air Medical Service Base 2] base site and went to the aircraft. I booted up the aircraft and noted there was not a red square or MMEXC0061 indication on the CDS. I go inside and find [the pilot] in the bed in the pilot's quarters with the lights off. I tell him I can't get the same indication. He tells me that you have to switch the rotary knob to 'M' to see it. I go back outside and make note that the Display Selector Switch; aka rotary knob; is in the 'T' position. I boot the system up again; no indication. I change the Display Selector Switch to 'M.' A red square and MMECX0061 appear on the CDS. 'M' is where you look at previous faults. I spend about the next hour looking through maintenance manuals to see what inspections had to be done for a Mast Moment Exceedance. I find the Conditional Inspection and find that it is dependent on the longevity and severity of the exceedance. I then attempt to find out how to retrieve more information from the CDS on the severity and longevity of the exceedance. I was also attempting to find out what 'MMECX0061' meant. I was unsuccessful. XB:13; unable to find the information; I call the [Technical Support] on-call number. They take my name and contact info. XB:15; the on-duty [Technical Representative] calls me; and we talk for about an hour and a half. He is also unfamiliar with the older CDS system but is able to find information about how to reset it. Through our research; we are able to find out that 'MMEXC 0061' is actually the longevity of the exceedance expressed as 61-time intervals of 200 milliseconds each. By multiplying 61 times 200ms; we reach a pretty long interval of 12.2 seconds above the 76% threshold. We double check the math several times and actually perform internet searches to acquire conversions to ensure the math is performed correctly. Essentially; the pilot would have to hold the cyclic very far from center for 12.2 seconds with a loud gonging sound in his headset every two seconds. That sounded far-fetched to me. I was hoping to find a time/date stamp on the exceedances. Was it one long event; or an accumulation of several? It seemed unlikely that it was an accumulation. Any exceedance; according to [the Technical Representative]; would give either a flashing red or solid red square on the CDS at the next boot up. So; that left it in my mind; that the CDS had recorded one long; 12.2 exceedance. In the attempt to narrow down when this might have occurred; I woke up the on-duty pilot and asked him if the red square had been on before; i.e.; when he came on shift and did his oncoming walk around. [The pilot] stated he didn't know. I asked him if it came on during the boot up when the #1 ENG CHIP DETECTOR CT indication came on during his first boot up of the system. [The pilot] stated it did not come on. It only came on during his second boot up of the CDS in the attempt to clear the #1 ENG CHIP DETECTOR CT fault. That led me to believe that the exceedance may have been recorded between the two boot ups; while the aircraft was static on the ground; on a very humid night that I also believed caused the initial #1 ENG CHIP DETECTOR CT' indication. This may be an indication issue caused by moist night air and not an actual exceedance. That may sound far-fetched but such false indications are not unheard of in our humid environment. Regardless; without a time stamp to prove that; I was resigned that I would have to follow the more stringent guidelines of the Maintenance Manual. This stated that any exceedance over 95% on a CDS system would have a lengthy conditional inspection on the Main Rotor Blades; requiring their removal. There are actually two different inspections; one if you have a CDS and one if you have a CPDS (Central Panel Display System). The difference is that the CPDS can actually tell you when the occurrence happened and how severe it was; so you don't pull the MR (Main Rotor) Blades unless they are especially harsh. You check several areas on the blades with them still installed; as well as the MR Mast. I wanted to at least talk about this to [another Mechanic] before I pulled the blades. Plus; I didn't have the resources to pull them. I start calling people and perform all the inspection items I can that didn't involve pulling the blades. I figured if I found evidence of damage that would be a show stopper. I didn't find any damage. XC:49; I call the on-call Mechanic at [Air Medical Service Base 1]. I was hoping that since [the aircraft] stays [there]; he may have had some more insight on this Mast Moment issue; such as if it has had false indications in the recent past. I was unable to reach him. XD:15 and XD:30; [I] attempt to reach [another Mechanic] because I'm running out of options other than pulling the MR Blades. XD:32 and XE:08; tried [to call the on-call Mechanic at Air Medical Service Base 1] again; no luck. At some point during these phone calls; and after I had inspected the MR Blades and Mast; I started heading out to start collecting tools. The tools necessary to pull the blades are 1 5/8 in. socket and a breaker bar; plus torque wrenches to put them back on. I did a brief search for those at the [Air Medical Service Base 2] site but the toolboxes were locked and I surmised that [they] had probably [been] taken to [City]. This was to pull the blades on [another aircraft] to allow taking it into the convention center. I had torque wrenches in the [Air Medical Service Base 3] service truck and I had the breaker bar and socket at my house. Pulling Main Rotor Blades is rarely such a spontaneous event; so I don't keep such large tools in my personal vehicle. [The Air Medical Service Base 3] site is an hour away from the [Air Medical Service Base 2] site. Then it was going to be a little over an hour to get from [Air Medical Service Base 3] to my residence; if traffic permitted. Then it would be about another hour and half to get from my residence back to the [Air Medical Service Base 2] site. So; some of the calls to [the on-call Mechanic at Air Medical Service Base 1] at this point was to try and get him to at least meet me halfway with a socket and a breaker bar; if not come to [Air Medical Service Base 2] and maybe help me pull blades if I could enlist a third person.I wanna take a minute here to say how dangerous it is to try and remove these blades with just two people. You really need three; so that the guy on the head can pass down the blade to someone on the ground. Four is actually optimal. If we drop the blade; it will probably damage the blade beyond economical repair and damage the aircraft on the way down; if not injure someone trying to 'save it' as it falls. XE:14; I call [another person]; hoping that even if he isn't the on-call guy; maybe he can give me some insight into the Mast Moment System on Aircraft X. He can't give much guidance on the Mast Moment; but this is when I learn that he is going to [State] and [the on-call Mechanic at Air Medical Service Base 1] is going to [City]. That means that; not only can I not count on manpower from [Air Medical Service Base 1]; I'm the only [Company] Mechanic in the region since [another Mechanic] is out of town and [the other Mechanic] is also going to [City]. I get to [Air Medical Service Base 3] and start moving my personal tools and equipment over to the [Air Medical Service Base 3] service truck. I notice that [an aircraft] is not on the pad. XE:44; I get contact with [another Mechanic]. He tells me that Aircraft X did have an issue with statically recording exceedances due to moisture in the past. [He] says that you could have the CDS booted up; statically on the ground and that the Mast Moment would fluctuate and record the fluctuations as exceedances. Things were further complicated by the fact that the CDS has been changed out a couple of times on Aircraft X and it was unclear if the Mast Moment Exceedances has been reset during bench testing. These recorded exceedances could be from another aircraft all together.We do know that if an item is not specifically mentioned on the work order at the CDS repair station; that work is not done; i.e.; a CDS went in with an issue that was written up and also several LCDs of the Fuel Quantity inoperative. Only the written up issue was resolved and the CDS was sent back to us with an unusable Fuel Quantity Indication. In the case of Aircraft X; a first-generation seal was replaced with an updated version around the connector for the Mast Moment Sensor. That alleviated the problem then. [He] states that this is probably due to moisture/water getting into a connector under the MR Hubcap support. We elect to have me go back and check it for moisture. I decide to leave the [Air Medical Service Base 3] service truck and return in my personal vehicle. I bring the case of torque wrenches with me just in case I need them. The sun is coming up as I head back to [Air Medical Service Base 2].XE:57; I call the on-duty pilot the day before. I ask him if he noticed any exceedances on his pre-flight or during his 0.8 hr. of flight that day. He states 'no' to both. I tell him what's going on and he can't think of any event or landing that could have caused the exceedances. [He] flew Aircraft X [yesterday] and the day [before yesterday]. Before him; it was ferried by [a ferry pilot] from [Air Medical Service Base 1] to [Air Medical Service Base 2]. XF:18; I call [the ferry pilot]. No answer. XF:25; [the ferry pilot] calls me back. I ask him if he had any issues with Mast Moment on Aircraft X on his ferry flight. He states there were none. I brief him on what's been going on since XA:00 and how I believe it could be just moisture. He seems to think that's plausible.I get back to [Air Medical Service Base 2]. [The on-duty pilot the day before] and [the duty pilot for Air Medical Service Base 2] are both there. We have an in-depth discussion planeside about the discrepancy; the things that we know and the things that have been done to inspect the aircraft. I tell them that we believe it is moisture in a connector and that I had planned to pull the MR Hubcap support to check for it. However; at this point; the sun has been up for some time and has burned off all the moisture in
EC135 Technician reported making a mistake during the write-up and sign-off of records and releasing an unairworthy aircraft due to fatigue.