Date: 201301
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 100
Light: Night
Aircraft: M-20 K (231) / Encore
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Training
Flight phase: Cruise
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Electrical Wiring & Connectors
Component problem: Malfunctioning
Reporter organization: Personal
Reporter function: Instructor; Pilot Not Flying
Reporter qualification: Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Anomaly: Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted; Flight Crew Landed As Precaution; General Declared Emergency
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: The aircraft owner and I departed IFR after filing an IFR flight plan and receiving a standard weather briefing. This particular flight was one of the last legs of a multi-day insurance transition training and a new engine break-in-period cross country trip. Immediately prior to the departure we cleaned off residual; very light frost from the wings. Upon engine start; we engaged the defroster to clear the windshield of any condensation built up by the two warm bodies entering the cold cockpit. After the windshield cleared; we engaged the cabin heat. The Mooney 231 heating ducts come through the bottom of the center console and spill the heat out over the fuel selector. Upon departing the area and on oxygen; we climbed to a final cruising altitude of 16;000 in VMC.About 25 minutes after entering cruise; we detected the faint; but growing smell of some plastic/electric mixed odor. The smell almost resembled the same stench that old aircraft put out when the heater is engaged; I have experienced this unpleasant; but uneventful smell many times. Five minutes after verbally noting the smell; it got a little stronger. Thinking that [having] the defroster on since departing; had potentially caused some type of moisture to contribute to the problem; we decided to fully close the defroster and partially close the cabin heater while opening the overhead vents. Our brand new carbon-monoxide detector showed a slightly different color than its original state; but not yet matching the caution or warning colors. Shortly thereafter; my client -- who was flying in the left seat -- stated that his right leg was a little warm. I leaned over and used my head lamp to inspect the forward cockpit area and below the instrument panel for any signs of smoke or flames. No such evidence was ever found; however something was very hot to the touch to the point where it created a light surface burn on two of my fingers. At this point we agreed that we should start identifying our best potential course of action in the event that we divert. An integral part to this process was notifying ATC that we had 'some type of smoke smell in the cockpit; no confirmed flames or visible smoke. We are not declaring an emergency yet but would appreciate information on possible alternates. What are my longest runways; weather conditions; and services available for airports within the next 75 miles?' ATC replied with all of my requested information and we determined the best potential alternate without having to traverse a long distance over mountainous terrain at night. I demonstrated how to input potential alternates into the G-430 at the end of the flight plan to allow for a quick direct-to decision. The circuit breakers; switches; lights; engine systems; ammeter; and other systems were checked and re-checked as part of our troubleshooting process -- we found no abnormalities. We accomplished; with the help of ATC; everything we saw fit to expeditiously facilitate a diversion if necessary. Five minutes later; I again attempted to inspect; to the best of my ability given the tight cockpit area; the forward cockpit areas (forward and below of the instrument panel). While leaning over the pilots side; I discovered a white; medium sized; zip tie that had dark stains emanating from a disconnected and glossy portion of its bottom half where it had melted. Upon a second look; this zip tie could have been the cause of the smell; therefore I reached forward to remove the zip tie; the potential source of the smell; in order to inhibit the production of further fumes. While performing this action; two white wires temporarily connected and created blue sparks. Upon seeing the sparks I immediately declared an emergency out of an abundance of caution and prudence. I requested and proceeded direct to [the nearest airport] at which time the Controller granted the request and asked essential questions concerning our flight (souls on board; flight conditions; cabin conditions). Notknowing whether the sparks were continuing; I requested a confirmation that emergency services were standing by in the event of an onboard fire or any other situation. We fully closed the cabin heater and confirmed the closed position on the defroster; not knowing their potential contribution. We continued to have the avionics and master switch engaged in order to conserve communication and transponder services; these switches appeared to not make the problem worse. I briefed the procedures for the remaining 12 minutes of the flight with my client so that we would be completely on the same page for any situation. We agreed that I would maintain the radio communications throughout the duration; on an extended final I would gain PIC control of the aircraft for the night landing; and he would execute any requested task to safely complete the flight. We agreed that if a fire were to break out; which it never did (no flames or visible smoke) we would shut down the aircraft as soon as possible on the runway and exit the aircraft via the main cabin door. Shortly after being handed off to another Controller; we called the airport in sight and switched to the advisory frequency. I performed a straight-in-approach for the south runway because it facilitated the quickest entry to the airport. No traffic was in the area. We completed all necessary pre-landing items and continued to complete the landing and roll-out. Upon landing; the emergency vehicle began to trail us for support. We determined that there was no fire or smoke; therefore we continued onto the taxiway and proceeded to the ramp via the emergency vehicles' direction. After the 3 minute turbo cool down time; we shut the airplane down in accordance with the checklist and exited the airplane and greeted the emergency personnel. One of the responders notified ATC via telephone to confirm our safe completion of the flight. After securing the airplane; I visually inspected the problem area and found that two wires; and their shrink wrap; had split from the unknown 6' cylindrical item that had burned my fingers. We later determined that the item was the resistor for the high and low fuel boost pump. No further marks of the incident were discovered via visual inspection other than the; already obtained; melted zip tie. We each had a full meal and coffee before the flight; including a bathroom stop; during a 1-hour break. We were both feeling very well physiologically and mentally to complete the flight. This was the 7th time that I had flown this aircraft during the past month; the second at night; and the 6th since the pre-buy and annual inspection; therefore I was comfortable with the trending performance and vital signs of the aircraft; no previous abnormalities had occurred during the flights. We were both unfamiliar with the area; however the sun was setting and a 3/4 moon existed with clear skies; and we were on an IFR flight plan. Our oxygen supply was enough for 10 more hours of dual use; and we had full fuel tanks. The night conditions; and thus the ambient darkness; played a factor in our ability to quickly determine exactly where and why the issue was occurring. We both had flashlights/headlamps; and the aircraft ambient lights performed flawlessly. This was the first flight originating from a cold airport; thus the performance of the defroster was unknown; we had frequently used the cabin heat during the previous flights with no abnormalities. Very low traffic volume and the low workload phase of flight afforded a large quantity of attention to troubleshoot the issue while maintaining IFR tolerances; especially with two pilots. ATC performed their duties flawlessly and proved to be a huge help for the safe outcome of the flight. I made the decision to declare an emergency; after seeing the sparks; immediately and without discussing it with my client; however we had prepared for the situation and I did not want to take ANY chances of having an onboard fire. I would have liked to have taken 5 seconds and verbally agree with my client that we were declaring an emergency. Also; I always remove my coat before flying because the cabin often gets too warm; thus creating an uncomfortable and distracting environment. However; after we closed both the heater and the defroster; the cabin became very cold; thus causing me to shiver. The shivering might have slightly degraded my aircraft control ability as well as slightly inhibited radio transmissions. Otherwise; we utilized everything within our disposal to land safely as planned. Two nights before the event; I attended a threat mitigation seminar that reiterated; among other things; to not hesitate in declaring an emergency. That recent discussion certainly aided my clear; methodical; deliberate; and safe decision making process.




Synopsis: M20 instructor pilot detects a burnt plastic smell at 16;000 FT during cruise. Investigation under the instrument panel produces electrical sparks. An emergency is declared and the flight diverts to the nearest suitable airport.