Date: 202003
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Cessna Aircraft Undifferentiated or Other Model
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Ferry / Re-Positioning
Flight phase: Takeoff / Launch
Airspace: Class D ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Engine Indications
Component problem: Improperly Operated
Reporter organization: Personal
Reporter function: Pilot Not Flying
Reporter qualification: Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Troubleshooting; Time Pressure; Confusion; Distraction; Fatigue; Human-Machine Interface; Situational Awareness
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Rejected Takeoff; General Flight Cancelled / Delayed
Contributing factors: Aircraft; Human Factors
Primary problem: Human Factors

Narrative: A chain of events culminated in a rejected takeoff that likely would have resulted in a low level in flight engine failure had the takeoff been continued. The mission was to deliver Aircraft X on amphibious floats to ZZZZ. With the current coronavirus restrictions; most flights have been canceled. Our originally planned flight that morning was canceled and we therefore had to reschedule on a flight much earlier in the day that gave the Pilot In Command (PIC) limited time to rest. He later disclosed after this event that he had gone to sleep [for only 2 hours]. I had gotten about 6 hours of sleep the night before and napped on the flight down. The PIC has over 600 hours of [Aircraft X type] experience and lots of amphibian experience. I have a lot of experience on amphibious floats in aircraft such as Super Cubs. I had never flown a [Aircraft X type]; and therefore was unable to obtain insurance for the trip. My turboprop experience was limited to agricultural planes. However; I was required to go along since I have a [foreign] pilot's license for the flight portion in ZZZZ.When we arrived to the FBO (Fixed Base Operator); we were told the fuel truck was finishing on other aircraft. As as a result; the PIC stated he was tired and need to take a nap. While he slept in the FBO; I went out to the aircraft to sort out the cargo and also familiarize myself with the cockpit setup. I re-arranged the cargo and secured it in the heat; and then began to pre-flight according to the POH. I also familiarized myself with the inertial separator bypass handle; including a function check; but did not know what it did. I spent about an hour on the pre-flight; including pumping water out of the floats and cleaning the windshield. I was distracted several times throughout the pre-flight by the fuelers asking about the tanks; and then having to reference the POH since I was unfamiliar with the fuel system. The sun was high in the sky; and therefore difficult to see the aircraft from below. There was no reference to the cowling inlet plugs in any of the conversations with the customer or pre-flight checklist. They were black and flush with the cowling. The propeller was also partially blocking them; and with the sun conditions it was difficult to see them. Additionally; they could not be seen from the position of the floats and when I eventually removed them; required quite a bit of stretching forward to get to.After the PIC woke up; he came out to hand me the suitcases. I loaded those into the plane. We began the pre-flight procedures. It became quickly apparent that the PIC was a little unfamiliar with the plane; since it had been so long since he flew [Aircraft X type]. I went over the checklist with him and showed him the location of all switches since I had spent the previous hour going over it by myself. We then started the airplane normally. The first sign of trouble was the standby power system; which was showing it was on; likely due to low generator output. After performing a function check per the checklist; the problem seemed to go away when we gave it power. The PIC selected the handle out of feather and into high RPM; with the condition lever in high idle. The RPMs failed to come up into the green. He said that something was wrong; but I wrongly insisted that the [other type reporter fly's] always required a lot of gas in order to come out of feather. We laughed about it; shrugged it off; and finally gave it enough power to taxi out. In hindsight; I shouldn't have offered my professional input for a plane I had no experience in; since I didn't know what normal looks like.During the run up; more signs of trouble showed themselves. The runup was normal except that the internal reference bypass test was unable to be performed due to the handle being completely jammed. He went to turn the handle and I assumed that he just wasn't familiar with it since I had tested it earlier. I then went to turn it and it was completely jammed.Instead of taking a step back to see what the problem could have been; he said that he is OK with continuing as long as the bypass is in and locked; the normal position for flight. We were both tired; very sweaty; and under pressure from the customer; and agreed that it would probably be OK in the normal position. However; I didn't know what this system even was and what effect it had on the system. We started the takeoff roll and immediately noticed climbing ITT [interstage turbine] temperatures close to the limit. The PIC said 'this isn't right; the torque is low; but we can continue the takeoff' The torque was around 18 or so; whereas normal takeoff is around 25. ITTs were close to limit; and prop RPM was up. I didn't know what was normal and so I had no frame of reference. About halfway down the runway and just over 70 knots; we realized something wasn't normal. I had never taken off in [Aircraft X type]; and although I knew they had a lot of performance; I was merely comparing us to how a fully loaded [aircraft pilot is familiar with] would handle; which can be a dog even with all the power. The PIC decided with my concurrence to abort the takeoff and stopped with about 2000ft remaining. I announced that we were aborting; and the aircraft on final was given go around instructions. We pulled off the runway at which time we were searching the gauges desperately for an answer. I then saw very low oil pressure; still with limits; and temperature was very high. I then realized the problem; that the engine wasn't getting air; and had him shut down to avoid any damage since adding power to taxi was getting us close to maximum ITT. I stepped out on the floats and pulled the cowling plugs out. They were still snug in their position. The spinner and prop didn't touch them. They were dull black on the outside and flush. They were still intact; nothing was sucked into the engine. We filled out paperwork with airport rescue vehicles. I stated the reason for the abort was abnormal engine indications; which proved to be correct. The pressure imposed on the inertial separator from the cowling plugs covering air intake caused it to warp and cave in; jamming the door partially open. This is why the handle wouldn't move - the door was jammed. We had the airplane towed to maintenance; where a new inertial separator was ordered; a quite expensive lesson to learn. The mechanics said the damage likely happened immediately after startup. However; the bigger lesson here was that 2 several thousand hour professional pilots;having flown over 120 different types of aircraft each; with several heavy jet type ratings; foreign licenses; and airline PIC experience nearly caused an in-flight engine failure despite having multiple indications of a possible problem. Had we continued that takeoff; the engine would have over-temped and quit over downtown [city]. Although this could be blamed on something as simple as missing a pre-flight item; the bigger problem is that fatigue and distractions combined with inexperience and a willingness to take unnecessary risk nearly led to disaster. In the future; I will be careful to not justify things that are abnormal in areas that I'm unaware of; and never continue the flight when a pre-flight check shows a failed item; especially on a system I don't know anything about.




Synopsis: A pilot ferrying an aircraft reported a rejected takeoff due to abnormal engine indications from not removing the cowling inlet plugs.