History of Flight
On November 12, 2017, at about 1730 central standard time, a Cessna T210N airplane, registration N5300A, experienced a loss of engine power and landed short of runway 9 at Campbell Airport (C81) in Grayslake, Illinois. The commercial-rated pilot, the sole occupant, was not injured. The airplane sustained substantial damage. It was registered to and operated by Runzel Brothers Aviation LLC under Title 14 Code of Federal Regulations Part 91 as a business flight. Night instrument meteorological conditions prevailed, and the flight operated under an instrument flight rules (IFR) flight plan. The flight departed Pierre Regional Airport, Pierre, South Dakota, about 1435 and was en route to Chicago Executive Airport (PWK), Wheeling, Illinois.
The pilot reported that during the en route portion of the IFR flight, engine indications were normal. About 1715, he noticed the oil pressure had decreased into the yellow arc, but other instruments showed normal indications. Shortly after, the air traffic controller instructed the pilot to descend to 2,500 ft mean sea level (msl). When the airplane reached 2,500 ft, the pilot heard a loud bang from the engine, and the cockpit filled with smoke. He declared an emergency and requested vectors to the nearest airport, C81. About 700 ft above ground level (agl), he descended out of the cloud layer and identified the runway lights. The pilot was very familiar with C81 and planned to land in a wetland area short of runway 9 because he could not glide the airplane to the runway. He left the landing gear retracted and landed in the wetland area, slid across a flat wooden bridge, and came to rest on runway 9.
Aircraft Information
The airplane was powered by a six-cylinder Continental Motors IO-550-P6B engine, serial number 1005420, modified via Vitatoe Supplemental Type Certificate (STC) SA02918CH to a turbo-normalized induction system. The modified engine was installed on April 2, 2012. The last maintenance logbook entry was on July 27, 2017, at a tachometer time of 1,010.1 hours, indicating compliance with airworthiness directive AD 71-09-07R1 (exhaust system inspection) and installation of a new fuel injector and cylinder head temperature probe. The last oil change was performed on June 29, 2017, at tachometer time 1,001.73. The last 100-hour engine inspection was on November 1, 2016, at the time the engine was reinstalled after a top overhaul. The pilot stated he could not remember the exact oil level and did not recall anything out of the ordinary during preflight inspection, nor any oil on the ramp or white smoke upon engine start.
Wreckage and Impact
The airplane landed in a field about 300 ft west of the runway 9 threshold, sustaining damage to the fuselage and elevator. After the accident, the pilot recalled oil covering the bottom fuselage and on the runway where the airplane came to rest.
Engine Examination
The engine was removed from the airframe and examined under supervision of a National Transportation Safety Board investigator. Examination revealed no evidence of ground impact or fire damage. The crankcase exhibited two large holes: one near the No. 4 cylinder and another between the Nos. 3 and 5 cylinders. All six cylinders remained attached; the No. 4 cylinder showed mechanical damage to the skirt and two attachment studs had broken free from the crankcase. Inside both crankcase halves displayed mechanical damage concentrated near the holes. The No. 4 connecting rod had separated from the crankshaft and displayed thermal damage signatures. All connecting rod bearings exhibited smear-type signatures; the No. 4 bearings were significantly damaged. No signs of fretting on bearing supports or evidence of bearing shift were found. Oil galleys showed no blockages. The oil sump, oil pickup tube, and screen remained intact and undamaged, containing a significant amount of metallic debris. The oil pump remained intact and undamaged, with a few metallic flakes and minor gouging along the housing. The oil filter remained attached with no anomalies, and its pleats contained significant metallic debris. The oil cooler was intact with no signs of an oil leak or anomalies. No blockages were noted in any oil lines; however, since the lines had been removed for shipping, the b-nuts could not be checked for tightness. The turbocharger oil scavenge check valve spring was found broken, and the flapper valve would not close automatically. No other anomalies were noted with the engine.
Additional Information
An AuRACLE CRM 2100 engine monitor data showed that oil pressure remained steady for about the first 2 hours of flight, then began to decrease. Over about 42 minutes, oil pressure decreased steadily from 51 psi to about 13 psi. When oil pressure dropped below 30 psi, oil temperature began to increase steadily until the total loss of engine power.
According to the STC owner and turbocharger manufacturer, the broken check valve spring that prevented automatic closure of the flapper valve would allow oil to enter the turbo after engine shutdown. Oil could leak into the compressor/induction and turbine/exhaust areas, and small amounts could be consumed during subsequent engine starts. Typical signs include oil leaking from the exhaust pipe and pooling under the airplane, and white smoke during engine start. The broken spring would not have caused a restriction from the turbo to the scavenge pump. Per the engine manufacturer, when a scavenge check valve does not close properly, oil in the line pools in the turbocharger while the airplane sits on the ground, resulting in a small amount of oil loss. During engine operation, an open check valve would not affect oil consumption.