Pilot's Account
The pilot reported that approximately 150 miles southwest of Monterey, the right engine began making unusual noises, ran rough, and exhibited high cylinder head temperature at the gauge limit. He advised Oakland Center of his position and situation but did not declare an emergency. Attempts to open the right engine cowl flap were unsuccessful due to a malfunction.
Remedial Actions
To cool the right engine, the pilot increased fuel flow to that engine. Eventually, he had to reduce power on the right engine to keep it running. To compensate for the power loss, he added power to the left engine. These actions increased fuel consumption beyond the planned burn rate. The asymmetric power condition also caused a periodic unporting condition in the outboard fuel tank pick-ups.
Fuel Management
The pilot switched to the inboard tanks until their supply was exhausted, then attempted to feed from the outboard tanks. He reported being unable to maintain consistent engine power output.
Ditching
The pilot was forced to ditch the aircraft approximately 20 miles short of the coastline.
Flight Plan and Duration
The pilot's VFR flight plan indicated a total en route time of 13 hours 10 minutes with 14 hours of fuel onboard. The elapsed time from departure to ditching was approximately 13 hours 12 minutes.