Incident Overview
A crew returning to Europe after participating in the AirVenture airshow in Oshkosh made a fuel stop in Goose Bay before continuing to Narsarsuaq, Greenland. The initial cruise level was FL210, but ATC instructed a descent to FL180. The pilot set cruise power to 65% (26.5" MP and 2,400 rpm), with a fuel flow of 14 gph leaned to a TIT of 50°F LOP. En route weather was 'nice' and mostly VMC, with an OAT at FL180 of approximately -10° to -15°C.
Descent and Warning
After contacting Nuuk Information upon entering Nuuk FIR, the pilot reported a descent from FL180 to 11,000 feet inbound to the IFR reporting point SIMNI at 1304LT. A 500 fpm descent was initiated with the same cruise power setting. While passing FL160, an 'unusual, electrical, and not very strong smell' was briefly noticed. The cabin altitude began increasing at 3,000 fpm, and the CABIN ALTITUDE annunciator warning light illuminated. Since the aircraft was below 15,000 feet and descending, the pilot considered the time of useful consciousness and did not don oxygen masks.
Emergency Declaration
At 1316LT, the pilot declared a Pan-Pan for an air conditioning problem and low oil pressure. The MP dropped from 26" to 17-18", and moving the throttle forward had no effect. All CHTs were normal and balanced. Moving the mixture control to full rich caused the engine to nearly stop; the pilot retarded it back. The aircraft was trimmed for best glide at 90 knots. At 1317LT, while descending through 12,000 feet, a Mayday was declared: 'high rpm now and will try to make it to the shore.' The ELT was activated. A RDAF surveillance aircraft and a RDN inspection ship were allocated to assist. Descending through 7,000 feet, propeller rpm increased to 3,000, and 30 seconds later oil pressure indicated zero. The pilot stopped the engine by pulling the mixture to idle/cut-off. A knee-mounted tablet showed the predicted gliding distance fell short of the coastline. At 1326LT, the expected ditching position was reported to Nuuk.
Ditching and Rescue
The pilot and passenger prepared for ditching: checking the life raft location, zipping up their survival suits (already worn up to their waists), and tightening seat belts. At 1329LT, while passing 3,300 feet, the RDAF aircraft spotted the gliding aircraft over a low overcast. The aircraft entered the cloud layer at 1,700 feet and exited at 700 feet. The RDAF aircraft had to reposition to maintain visual contact. Visibility below the cloud layer was 'good' and sea surface had 'only low swells'. At 1333LT, the pilot selected flap 20°, slowed to minimum airspeed, and flared. The aircraft bounced once on the sea surface, then hit a second time, decelerated abruptly, and stopped floating in a wings-level position. The occupants released seat belts, went to the aft cabin, opened the top of the door (above water), deployed the life raft, and stepped into it. At 1340LT, the RDAF crew spotted the life raft. The RDAF aircraft circled overhead for 45 minutes. At 1400LT, the pilot contacted Nuuk FIC via satellite telephone. At 1423LT, a rescue crew from the RDN inspection ship in a RHIB picked up the pilot and passenger. The aircraft sank approximately 2 hours after the ditching.
Probable Cause
The official investigation determined that an engine failure during descent resulted in a ditching off the southwest coast of Greenland. The AIB could not determine the exact cause of the engine failure but stated it was likely due to a seeping oil leak. The accident was survivable due to a combination of factors: the pilot's timely urgency and distress declarations, visual contact by a nearby RDAF aircraft, successful landing on calm sea, wearing of survival suits and presence of life raft, and prompt rescue by personnel from a nearby RDN inspection ship.