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Cirrus SR20 Engine Failure

posted Apr 17, 2011, 2:44 PM by George Finlay   [ updated Oct 8, 2011, 11:02 AM by Nathaniel Cauldwell ]

At 1405Z on February 2, 2007, a typically cold day in Goose Bay Labrador (CYYR), three pilots departed together in three new Cirrus SR20s carrying registration numbers N901SR, 806SR and 720SR. They filed for Reykjavik, Iceland (BIRK), 1350 nm east, on the first leg of a delivery flight to Phuket, Thailand. Each plane carried a ferry tank in the back seat with 80 US gallons additional fuel. Fritz Schoeder, a Swiss living in Florida, had the delivery contract. He had subcontracted with pilots Michael Bradford, an American, and Siggy Lehr, a German living in Florida.  It had been equally cold on earlier legs from the Cirrus plant at Duluth MN (KDLH), 1300 nm west. For this leg, Fritz Schoeder flew N901SR, while Michael and Siggy piloted the other two. When an enroute weather briefing reported deteriorating conditions at Reykjavik, the flight of three diverted toward Narsarsuaq (BGBW), about 675 nm from Goose Bay.

They were about 100 nm out when Fritz, flying at 13,000 feet, first reported fluctuations in his oil pressure and temperature. Michael, who had been in the lead plane at 9,000 feet, circled back to trail Fritz with Siggy, in case he could not make BGBW, and at 1729Z Fritz advised ATC at Sondrestrom in Greenland, that he might have to declare an emergency. ATC immediately notified Sondrestrom Rescue Coordination Center.  At first Fritz thought it was a problem with the gauges, but at 1749Z, he declaring the emergency.

By early 2007, the SR20 fleet had already accumulated a record of oil breather tube ice blockages on the Continental IO-360-ES engine, which had led Cirrus to issue a winterization kit and a non-mandatory service bulletin #SB 2X-71-10, dated October 8, 2004. The problem was the location of the tube at the front of the engine, directly in the path of cooling air. There has never been a problem reported in the larger Cirrus SR22, which uses the Continental IO-550-N, with the breather line in the back of the engine.

Water vapor produced as a normal byproduct of combustion is intended to vent through the breather tube. But in extremely cold operating conditions the temperature inside the tubes in the SR20 sometimes stayed below freezing long enough to allow the water vapor to turn to ice, occasionally in sufficient quantity to completely block the tube. The tendency is increased at low power settings typically used to extend range on a ferry flight, which resulted in lower overall engine operating temperatures. Denied an outlet, the water vapor can causes a pressure increase over the oil in the pan, and drive it to break out elsewhere in the system, through the filler cap or dipstick tube, for example. The winterization kit restricted the flow of cooling air by reducing the size of the cowl opening and the service bulletin called for insulating the oil breather line.

Many Atlantic ferry pilots were aware of this problem and elected to install either or both the kit and the sleeve. Michael and Siggy had recommended to Fritz that they install the sleeve. Fritz, perhaps concerned about time and money, declined.

In N901SR, the situation quickly deteriorated. Oil appeared on the windscreen, oil pressure began to drop while oil temperature rose. Eventually the engine lost partial power, and the airplane began to descend. Fritz radioed his wingmen that he was heading for Simiutaq (SI), an NDB now about 50 nm northeast of his position at the mouth of the fiord that leads north toward Narsarsuaq, He said he hoped to be able to make an emergency landing near there if unable to make the field. He said to tell his wife he loved her.

There was a solid undercast which he did not break through until 800 feet AGL, by which time the engine had quit and he reported smoke in the cockpit. He could see land, but could also see it was not practical to land there, so he turned back toward the position he had last reported, 60 38N 46 41W, WSW of SI. By this time his altitude was only a few hundred feet AGL. His last radio transmission was about 1810 Zulu, as a AS350 rescue helicopter was departing Qaqortoq (BGJH) just east of SI. A few minutes later, a second helicopter, an S61, departed Narsarsuaq.  Michael and Siggy descended through the clouds and searched for the plane with the helicopters.

Visibility was good, the sea was calm, winds were light, but there were hundreds of small icebergs in the area, making it difficult to pick out a small white airframe. Siggy finally spotted the wreckage sitting nose down in water so clear and calm he could see the wings intact below the surface. The tail had been destroyed and the left door ripped off. Daylight only lasts about seven hours in that area in February, and it was getting too dark so the two SR20s headed for Narsarsuaq, while the helicopters continued the search. They soon found Fritz’s body near the wreckage, in a survival suit and a life preserver. While the helicopter crew was recovering the body, the rocket in the Cirrus airframe fired, spreading the parachute across the water.

An autopsy performed in Greenland concluded Fritz had drowned, though he also had a broken femur. The damage to the airframe in conjunction with the injury may indicate the plane struck one of the small icebergs while ditching. The airplane was not recovered.

Michael is now flying a Lear and Siggy is now an airline pilot. On May 24, 2007, Cirrus made the oil breather tube insulation mandatory in SB 2X-71-10 R1.

Links:

Map of accident area

Service Bulletin

Oil loss report in 2004

Accident report