Engine oil cooling is accomplished by an oil cooler and a bleed air driven turbine fan. The engine and transmission oil coolers use the same fan.

Engine Oil Supply System

The engine oil system is a dry sump, pressure type, and completely automatic. The oil tank is located in the upper pylon fairing. It will self seal a 30 caliber projectile hole and is equipped with de-aeration provisions. Oil is gravity fed from tank to engine driven oil pump which provides pressure and scavenging for the system. On helicopters with ODDS, an external oil separator, with integral chip detector , and a 3 micron oil filter are installed downstream of the sump.

Switching Action

The pilot ENG OIL BYP switch AUTO position permits the oil to automatically bypass the oil cooler when the oil tank is approximately 3.8 quarts low. The OFF position deactivates the automatic bypass feature causing the oil to pass through the oil cooler regardless of the oil tank level. The switch circuit is powered by the dc essential bus and protected by the FUEL OIL VALVE circuit breaker.