A Lead Mechanic reports he was informed the MEL deferral he made for an air interrupt B757-200; with an overhead hydraulic light problem; did not include a specific statement verifying the hydraulic system pressure was good.

Narrative

It was brought to my attention today of an incident that happened in September 2008. A B757 had an air interrupt with a Hydraulic Light problem. The aircraft arrived and went to a gate. I met the aircraft and interviewed the flight crew. They told me that there was a problem with an overhead hydraulic light. I took the logbook and called our company's B757 Maintenance Control and asked if I could get a placard. They said I could; but to check out the aircraft and determine that the hydraulic system was working and the hydraulic light was an independent problem. I got the Procedures Manual for the placard and also determined that the hydraulic system was working correctly with the EICAS and operating the controls and noting the drop in pressure and the immediate return to normal pressure. There was also no loss of hydraulic fluid and the quantity was full. The light was placarded per MEL and Procedures Manual; the aircraft released for service; and 757 Maintenance Control notified for follow-up. Callback conversation with Reporter revealed the following information: Reporter stated he performed the trouble shooting procedures per their Procedures Manual; as required per the MEL; to verify the hydraulic pressure was good; in order to defer the overhead light. He was not aware of any requirement to specifically state the hydraulic system pressure was good; since he had verified the hydraulic system pressure integrity during the trouble shooting procedures he was required to performed; in order to be allowed to defer the overhead light. Reporter stated he was also told the issue of specifically stating the left hydraulic pressure was good was due to the wording of the pilot's write-up; that included an EICAS message displayed and the overhead light coming on. He could defer the light or the EICAS message; but not both. The B757-200 flew for three more flight legs and the hydraulic light assembly was replaced. No further problems were noted.