B737-700 flight crew experiences low oil quantity during climb out with normal temperature and pressure. Oil gulping is suspected and the engine is monitored until pressure begins dropping during descent and the engine is shut down. A single engine landing ensues at destination ensues.
Synopsis
B737-700 flight crew experiences low oil quantity during climb out with normal temperature and pressure. Oil gulping is suspected and the engine is monitored until pressure begins dropping during descent and the engine is shut down. A single engine landing ensues at destination ensues.
Narrative
On takeoff/climbout; we experience a low oil quantity indication. Based on all other engine indications (normal oil temperature/pressure); we suspected 'oil gulping.' After climbout/level off; oil quantity began increasing but never completely returned to a normal level. After cruising for approximately 30 minutes; the oil quantity decreased and oil pressure slowly started to erode. We reviewed QRH procedures for Low Oil Pressure/Precautionary Engine Shutdown/Landing with One Engine and made the decision to execute a precautionary engine shutdown if oil pressure indicated 'red' (13 PSI). We also worked a decision matrix for nearest suitable airfield if we had to shut down the engine. At the top of descent; oil pressure was not yet below minimums. Passing 25;000 FT the oil pressure went below minimums and we elected to shut down the engine; declare an emergency; and proceed to destination. Landing was uneventful. Rescue crews scanned and cleared the airplane. We taxied to the gate uneventfully.'Oil gulping' is an interesting event. We have received training time devoted to it at recurrent training. The theme seemed to be that crews were returning/shutting down engines when it was not needed. I would say this mindset led us to assume oil gulping and continue (although we monitored the engine continuously for any other abnormalities). There is no guidance in any of our official publications/QRH for oil gulping. I think it would be helpful to have some type of checklist to back up the crew when such an event occurs in flight. It would help the decision making process.
Second reporter narrative
At rotation First Officer noticed engine oil quantity read zero. We recalled the letter regarding engine oil gulping. The First Officer found some reference in the Operations manual and FOM saying it happens during high power and initial climb but then slowly returns to normal and it is not a return to field event as long as oil pressure and oil temperature were normal. Engine indications remained normal and oil quantity slowly started to return but only reached 15% (approximately) engine parameters were normal. Numerous messages to Maintenance Control were sent. I think four. None were answered. We reviewed the engine shutdown procedures and monitored nearest suitable airports enroute along with drift down.About 100 miles out; oil pressure started to drop but oil temperature remained normal. APU was started in case of shutdown. While descending through about FL250; oil pressure dropped to 13 PSI (red box) and the QRH was followed and the engine was shutdown. An emergency was declared. Flight attendants were notified and equipment was rolled. A flap 15 landing was completed and a logbook entry was made. We found very little guidance on engine oil gulping. We would have found it helpful if Maintenance Control would have answered any of our messages. They did respond with (see you on the ground) after we told them the number two was shut down. The first message was sent informing them what was going on about an hour before we went single-engine.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.