CH750 / Cruzer
Flight Crew Private
Flight Crew Last 90 Days 65; Flight Crew Total 225; Flight Crew Type 78
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Landed in Emergency Condition; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft
As I was in the 45 approaching the turn to downwind for left traffic at ZZZ the power suddenly dropped and engine rpm fell significantly. Gearbox oil temperature rose rapidly and a burning smell entered cabin air. I did a check for fuel flow and switch to use both fuel pumps without effect. I rocked wings to see if it was a fuel feed issue. Appling a cruise power setting caused engine to sputter; but it produces some power at near idle speed. Insufficient power was available to perform a normal pattern and landing; so I [advised] on CTAF and informed the CTAF that I would be making a direct shortened base and final into the runway at ZZZ. With the altitude to glide to the air field and the little remaining power; I was able to cut the corner and get the plane in position for a short final with some excess altitude; performed a slip to bleed off the extra speed and landed without further incidence. The engine was running; but not making good power but enough to clear the runway and taxi to hangar area where I investigated and found oil leaking from seal at the front of the gearbox power shaft. The sight window to the gear box oil showed opaque black oil; rather than the clear light amber color normally present. Downloading the data logger showed a climb in Gearbox temperature followed by sharp drop in RPM followed by a extremely sharp rise in Gearbox oil temperature; rising more that 120 degrees Fahrenheit above normal operating temperature. The Gearbox was a upgraded model recently installed and had 15 flight hours on it. The manufactured recommended replacement with the new model based on better cooling and stronger bearings. The previous gearbox had flow for 50 hours with no failure; and was only replaced as recommended by manufacture because of design improvements. The aircraft was equipped with a Viking 130 engine; which includes the gearbox designed for the Viking 170 engine. Both are manufactured by Viking Aircraft Engines.
Pilot reported an emergency landing caused by engine power loss.