Narrative:

Small transport X, a BE90, departed ede VFR, requested IFR clearance to frederick, md. A flight plan was on file, so I activated it and radar idented X with traffic at 5000 ft, aircraft Y. I asked X to maintain 4000 ft prior to clearance, and called traffic. When X replied affirmative to the altitude, I then cleared X 'as filed, maintain 4000 ft.' X rogered clearance, but shortly thereafter I noticed the conflict alert activate and noticed climbing through 4500 ft. I queried the pilot as to whether he was level at 4000 ft and he replied 'we're bringing her back down.' I believe the pilot, when hearing 'cleared as filed,' also heard his requested altitude (11000 ft), even though 4000 ft was issued. Supplemental information from acn 284604: small aircraft X was assigned an altitude of 4000 ft. At that point the airplane was leveled off and the autoplt was placed in the altitude hold function. The emergency red light, notifying me that the hydraulic fluid was empty, came on. In turn, I went to consult the emergency checklist and pilot handbook to find out the procedure in handling this emergency. At this point, ATC notified me that I had broken my altitude. In all that was happening, I notified ATC that I was bringing the airplane back to 4000 ft. At this point, I had so much going on that I was trying to fly the aircraft, hold the altitude and determine what to do with the emergency light for the hydraulic fluid. Please understand, I had no intention of breaking my altitude but I did not know the altitude hold was not on. In turn, I proceeded to familiarize myself with the procedure for landing and then received another call from ATC notifying me to call quality assurance, which I did when I landed. For some unknown reason, nobody answered that phone number. At that point, I called FBO and notified them that upon landing at fredericksburg, va, that the left wheel strut was saturated in red hydraulic oil. The decision at that point was to fly the aircraft directly from there to norfolk and under no circumstances was I to raise the gear back up.

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Original NASA ASRS Text

Title: SMT X NON ADHERENCE TO ATC CLRNC ALT DEV HAD LTSS FROM ACFT Y.

Narrative: SMT X, A BE90, DEPARTED EDE VFR, REQUESTED IFR CLRNC TO FREDERICK, MD. A FLT PLAN WAS ON FILE, SO I ACTIVATED IT AND RADAR IDENTED X WITH TFC AT 5000 FT, ACFT Y. I ASKED X TO MAINTAIN 4000 FT PRIOR TO CLRNC, AND CALLED TFC. WHEN X REPLIED AFFIRMATIVE TO THE ALT, I THEN CLRED X 'AS FILED, MAINTAIN 4000 FT.' X ROGERED CLRNC, BUT SHORTLY THEREAFTER I NOTICED THE CONFLICT ALERT ACTIVATE AND NOTICED CLBING THROUGH 4500 FT. I QUERIED THE PLT AS TO WHETHER HE WAS LEVEL AT 4000 FT AND HE REPLIED 'WE'RE BRINGING HER BACK DOWN.' I BELIEVE THE PLT, WHEN HEARING 'CLRED AS FILED,' ALSO HEARD HIS REQUESTED ALT (11000 FT), EVEN THOUGH 4000 FT WAS ISSUED. SUPPLEMENTAL INFO FROM ACN 284604: SMA X WAS ASSIGNED AN ALT OF 4000 FT. AT THAT POINT THE AIRPLANE WAS LEVELED OFF AND THE AUTOPLT WAS PLACED IN THE ALT HOLD FUNCTION. THE EMER RED LIGHT, NOTIFYING ME THAT THE HYD FLUID WAS EMPTY, CAME ON. IN TURN, I WENT TO CONSULT THE EMER CHKLIST AND PLT HANDBOOK TO FIND OUT THE PROC IN HANDLING THIS EMER. AT THIS POINT, ATC NOTIFIED ME THAT I HAD BROKEN MY ALT. IN ALL THAT WAS HAPPENING, I NOTIFIED ATC THAT I WAS BRINGING THE AIRPLANE BACK TO 4000 FT. AT THIS POINT, I HAD SO MUCH GOING ON THAT I WAS TRYING TO FLY THE ACFT, HOLD THE ALT AND DETERMINE WHAT TO DO WITH THE EMER LIGHT FOR THE HYD FLUID. PLEASE UNDERSTAND, I HAD NO INTENTION OF BREAKING MY ALT BUT I DID NOT KNOW THE ALT HOLD WAS NOT ON. IN TURN, I PROCEEDED TO FAMILIARIZE MYSELF WITH THE PROC FOR LNDG AND THEN RECEIVED ANOTHER CALL FROM ATC NOTIFYING ME TO CALL QUALITY ASSURANCE, WHICH I DID WHEN I LANDED. FOR SOME UNKNOWN REASON, NOBODY ANSWERED THAT PHONE NUMBER. AT THAT POINT, I CALLED FBO AND NOTIFIED THEM THAT UPON LNDG AT FREDERICKSBURG, VA, THAT THE L WHEEL STRUT WAS SATURATED IN RED HYD OIL. THE DECISION AT THAT POINT WAS TO FLY THE ACFT DIRECTLY FROM THERE TO NORFOLK AND UNDER NO CIRCUMSTANCES WAS I TO RAISE THE GEAR BACK UP.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.