The aircraft involved in the accident, a twin-engine turboprop, was known to have a right engine that ran hotter and used more fuel in flight than the left engine.
In addition to the high fuel flow and oil temperature in the right engine, the aircraft had poor cockpit lighting at night.
Observation flights by the National Transportation Safety Board (NTSB) investigators found that errors in flap settings due to poor lighting were common on Twin Otters during night flights.
The area around the flap control overhead was not illuminated; and the flap position indicator on the windscreen center post was poorly illuminated to the point of being barely visible.
Some of the lights in the engine gauges had been incorrectly replaced with red, instead of white bulbs, making the gauges hard to see.
Pilots had requested the maintenance crew standardize on one color of light bulb, but this had not been done at the time of the accident.
Among Downeast pilots, there was discussion of the first officer's altimeter sticking and indicating as much as a 100 ft (30m) difference in altitude compared to the pilot's altimeter during descent and ascent.
There was no formal record of the altimeter problem in the aircraft's logbooks, but investigators were told that it had been checked during an inspection in the past with no defects found.
The aircraft involved in the accident, a twin-engine turboprop, was known to have a right engine that ran hotter and used more fuel in flight than the left engine. In addition to the high fuel flow and oil temperature in the right engine, the aircraft had poor cockpit lighting at night. Observation flights by the National Transportation Safety Board (NTSB) investigators found that errors in flap settings due to poor lighting were common on Twin Otters during night flights. The area around the flap control overhead was not illuminated; and the flap position indicator on the windscreen center post was poorly illuminated to the point of being barely visible. Some of the lights in the engine gauges had been incorrectly replaced with red, instead of white bulbs, making the gauges hard to see. Pilots had requested the maintenance crew standardize on one color of light bulb, but this had not been done at the time of the accident. Among Downeast pilots, there was discussion of the first officer's altimeter sticking and indicating as much as a 100 ft (30m) difference in altitude compared to the pilot's altimeter during descent and ascent. There was no formal record of the altimeter problem in the aircraft's logbooks, but investigators were told that it had been checked during an inspection in the past with no defects found.
Downeast Flight 46