B757 flight crew experienced a L ENG HYD OVHT EICAS advisory message just prior to descent. Crew landed safely and was informed by maintenance that the pump is extremely hot and leaking fluid. Reporters lament the lack of guidance in the QRH as to the potential seriousness of the problem.
Synopsis
B757 flight crew experienced a L ENG HYD OVHT EICAS advisory message just prior to descent. Crew landed safely and was informed by maintenance that the pump is extremely hot and leaking fluid. Reporters lament the lack of guidance in the QRH as to the potential seriousness of the problem.
Narrative
Just prior to top of descent; received EICAS advisory: L ENG HYD OVHT. Ran QRH procedure: 757 ENG HYD OVHT (L or R). First Officer and I discussed possible related problems and possible subsequent failures. We also reviewed our systems knowledge. We decided to continually monitor the hydraulic quantities; use longer runway; configure early; use longer final; and not overtax the left hydraulic system in order to be prepared for a possible escalation of our apparently slightly degraded hydraulic system problem. We accomplished what we briefed with no noticeable decrease in left hydraulic quantity and all systems operations normal. After parking at the gate with all checklists done; maintenance informed us that left engine hydraulic pump was in fact extremely hot and had been apparently leaking hydraulic fluid.First Officer and I discussed our mutual increase in concern over a checklist that could and maybe should have given us more insight or direction. In the procedure; a note or caution of possible related concerns might be helpful such as those we accomplished and reviewed as mentioned previously.
Second reporter narrative
We flew an uneventful approach and landing then taxied to the gate. Before descent I had requested maintenance meet the aircraft so we could debrief them about this issue. They were there as we blocked in; and shortly after entered the cockpit to tell us we indeed had a problem with our left engine hydraulic pump. He said that we had been trailing fluid for a while; and there was a stream of fluid all the way back to the entrance to the ramp and a pool of fluid under the engine. He also stated that the hydraulic pump was extremely hot. We all went down to the ramp to look at this with the engine cowling open; and it gave us reason to pause. It also gave both of us a desire to write this event up in an effort to determine if more information could be made available for the cockpit crew to analyze while dealing with these types of situations. Had we known that we were dumping hydraulic fluid overboard and the extent of the heat build up in the engine; we would have seriously considered declaring an emergency; so we could get right into the field without delay. What would be the outcome if the hydraulic pump had run dry; or overheated to the point of failure. What if it had happened earlier in our flight instead of at the end? The procedure in the QRH for this is very vague; and does not provide us with notes; warnings; or cautions that we could use as safeguards in watching out for more serious complications arising from this seemingly benign abnormal. This is the second report I have filed in my last two trips. My previous trip I wound up shutting down an engine in flight and diverting after first getting a 'R ENG OIL FILTER' bypass message. Here it stated 'Crew Awareness' and that was all. An hour down the road; we started rapidly loosing oil quantity in that engine and shut it down as a result in the descent. Our experience and training; along with a fundamental understanding of the system helped us look out for potential problems that came from these rather benign scenarios. Incorporating notes; warnings; and cautions into QRH procedures would provide a set of things the crew could think about; and watch for as they progress in the flight. Without that thought process and with the loss of experience; old training techniques; emergency procedure guidance that used to be included as reference in our manuals; and the aging and retiring of our knowledge base; the information that I have been able to use in these past two situations is now missing from our books. In both instances; qualitative information on what could happen; or what you might loose or should monitor is not present. Also; I believe that if you have to contact Maintenance Control for support during an airborne situation; you should be able to reach and speak to a real; qualified-on-your-aircraft Mechanic; and not someone who is just answering the phone; and reading from a trouble book. There is just too much at stake to leave this intel out of the equation.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.