TFE731 Oil Pressure Woes
June 1, 2016
High and low pressure indications on TFE731 engines can be caused by several factors. One of the more common causes is a defective Breather Pressurizing Valve (BPV). Two ways to diagnose this issue are:
Oil Pressure Drops During Ascent
Oil pressure that appears normal below 27,000 ft. but drops as the aircraft climbs above this point is an indication that the BPV is not closing. You can remove the BPV and push on the bellows to see if they move (they should not move). If you are able to move them, replace the BPV. If the bellows do not move and appear normal, try swapping with the opposite engine. If the squawk is still present, you can contact Dallas Airmotive’s F1RST Support team to help diagnose and fix the problem on-site.
Oil Pressure Rises During Descent
Alternatively, if the oil pressure appears normal at altitude, but begins to rise as the aircraft descends, the BPV may be stuck closed. With a strong light, visually check the BPV. A rule of thumb to remember as you check the BPV is that the valve should be open at least .07 inches at sea level. A faulty bellows will cause the valve to be completely closed on the ground. If it is closed, the BPV likely needs to be replaced.
While a problem with the BPV is common culprit to oil pressure issues, it is not the only one. The recommended and safest course of action always is to contact an authorized TFE731 service center, like Dallas Airmotive, to help diagnose and fix any issues that may be occurring with your engine.
These Tips and Tricks are for reference and they are only a starting point. They are not intended to be comprehensive instructions. Please:
- Seek the assistance of a professional mechanic for all repairs beyond your capabilities;
- Consult the OEM’s applicable maintenance manual, and any Airworthiness Directives and Service Bulletins; and
- Remember that the cornerstone of aircraft safety is redundancy — the "second set of eyes" inspection principle is non-negotiable.