Circumstances:
The crew was returning to Europe after taking part to the AirVenture airshow in Oshkosh. Following a fuel stop in Goose Bay, the crew continued to Narsarsuaq, Greenland. The initial cruise level was FL210, but after a short while, ATC instructed the pilot to descend to FL180. The pilot set the cruise power to 65% (26.5' Manifold Pressure (MP) and 2,400 revolutions per minute (rpm)), and the Fuel Flow (FF) leaned to 14 US gallons per hour (gph) with a Turbine Inlet Temperature (TIT) of 50° Fahrenheit (F) Lean of Peak (LOP). The weather en route was 'nice' and mostly VMC, and the Outside Air Temperature (OAT) at FL180 was approximately -10° to -15° Celsius (C). The pilot contacted Nuuk Information (ATS unit Flight Information Center (FIC) Nuuk) when the aircraft entered Nuuk Flight Information Region (FIR). At 1304LT, in preparation for landing in BGBW, the pilot reported a descent from FL180 to 11,000 feet inbound to the IFR reporting point SIMNI (located at the Greenlandic coastline, 45 nm south-west of BGBW). The pilot initiated a 500 feet per minute descent and kept the cruise power setting at 65%. While passing FL160, the pilot and the passenger briefly noticed an 'unusual, electrical, and not very strong smell'. The cabin altitude started increasing by a rate of 3,000 fpm, and the pilot realized 'something was wrong'. Shortly after, the CABIN ALTITUDE annunciator warning light illuminated, indicating a cabin altitude above 10,000 feet. As the aircraft was below an altitude of 15,000 feet and descending, the pilot considered the time of useful consciousness and opted not to don the oxygen masks. At 1316LT, the pilot declared an urgency situation to Nuuk Information: 'Pan-Pan, Pan-Pan, Pan-Pan. We have an air conditioning problem and a low oil pressure indication'. The MP dropped from 26” to 17-18” and the pilot moved the throttle lever forward without any effect. All Cylinder Head Temperatures (CHT) indicated 'normal and balanced', and the pilot moved the mixture control full forward to the rich position. The engine almost stopped, and the pilot retarded the mixture control back to the previous position. The aircraft pitch was adjusted to obtain the best glide airspeed of 90 knots. At 1317LT, while descending through 12,000 feet, the pilot declared a distress situation to Nuuk Information: 'Mayday, Mayday, Mayday. We have high rpm now and will try to make it to the shore'. The pilot activated the aircraft Emergency Locator Transmitter (ELT). A surveillance aircraft from the RDAF and an inspection ship from the RDN were on patrol in the area. The Danish Armed Forces Arctic Command allocated both to provide assistance. While descending through 7,000 feet altitude, the propeller rpm increased to 3,000 rpm, and 30 seconds later, the oil pressure indicated zero. The pilot pulled back the mixture handle to the idle/cut-off position and stopped the engine to avoid major mechanical damage. The pilot observed on his knee-mounted tablet that the predicted gliding distance of the aircraft fell short of the coastline. At 1326LT, the pilot informed Nuuk Information of the expected ditching position: 60° 30' N 46° 45' W. The pilot and the passenger prepared to ditch by checking the location of the life raft in the cabin, zipping up their survival suits (which they were already wearing up to their waists), and tightening their seat belts. At 1329LT, as the aircraft was passing 3,300 feet descending, the RDAF surveillance aircraft spotted the aircraft gliding on a north-easterly course over a low overcast. At approximately 1,700 feet, the aircraft entered the cloud layer, and exited below at approximately 700 feet. The RDAF surveillance aircraft lost sight of the aircraft as it entered the cloud layer. In order to safely descend below the cloud layer in VMC, the flight crew of the RDAF surveillance aircraft had to fly to the coastline, descend, and fly back towards the expected ditching position below the cloud layer. The visibility below the cloud layer was 'good', and the sea surface had 'only low swells'. At 1333LT, the pilot selected flap setting 2 (20°), slowed down the aircraft to minimum airspeed, and flared the aircraft straight ahead. The aircraft bounced slightly on the sea surface once, before hitting the sea surface a second time. The aircraft decelerated fairly abruptly – 'similar to a hard brake in a car' – and stopped in a wings-level position, floating on the surface. The pilot and the passenger released their seat belts, went into the aft cabin, and opened the top part of the aircraft entrance door, which was above the water level. They manoeuvred the life raft through the entrance door into the water and inflated the raft. The pilot and the passenger threw a few personal items into the raft and stepped directly from the aircraft into the raft. At 1340LT, at position 60° 34' N 46° 50' W, the RDAF surveillance crew spotted the life raft with the pilot and passenger. For the next 45 minutes, the RDAF surveillance aircraft circled overhead the life raft. At approximately 1400LT, the pilot contacted Nuuk FIC via satellite telephone. At 1423LT, a rescue crew in a rigid-hulled inflatable boat (RHIB) dispatched from the RDN inspection ship and picked up the pilot and passenger. The aircraft sank approximately 2 hours after the ditching.
