Flight Crew Air Transport Pilot (ATP)
Training / Qualification; Troubleshooting; Workload
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Diverted; General Maintenance Action; General Declared Emergency
Aircraft
After takeoff and during gear retraction; we heard a thump followed by increased wind noise.  As the PF (Pilot Flying); I looked down and noted the gear indicating down with the gear handle in the up position.  We had three green gear lights and a red gear disagree light. On the EICAS; we had amber HYD VOLUME LOW A and HYD PTU FAIL. The quantity and pressure of the A side hydraulics both indicated zero. The hydraulic temperature was holding steady.  We were switched to Departure and advised them of our mechanical failure and the subsequent need to work with Company on our diversion airport of choice.  They provided delay vectors and climbed us to 5;000 FT to work the problem.  I; the PF; handled the radio while the PM (Pilot Monitoring) ran the HYD VOLUME LOW A checklist.  ATC asked if we would declare an emergency; and I replied in the affirmative.  Once the initial parts of the checklist were complete; The PM went to the back to explain the mechanical failure to our passenger and explained the need to divert.  The passenger was pleasant; calm; and understanding throughout the whole process.  As a crew; we decided a nearby airport would be an excellent divert airport given its light headwinds; long; wide runway and CFR (Crash/Fire/Rescue) services.  We advised ATC of our choice and set up our NAV radios for Runway XX.  The PM and I fully briefed the approach and landing requirements and our crew plan for landing using emergency braking and our lack of normal steering and reverse thrust.  Enroute; to the divert airport; the PM briefed the passenger on our expected normal landing with the potential for an emergency evacuation; he also explained our Company would be working on a recovery plan for his trip.  Again; he was very calm and understanding.  Upon return to the cockpit; I called Tower on the secondary radio to inform them of our emergency arrival in about 10-15 minutes and that we would be disabled on the runway.  We requested CFR be standing by as well as a tug.  The subsequent arrival; approach; and landing went as briefed and expected.  We shut down the engines and waited about 20 minutes while CFR monitored our brake temperatures for possible fire.   They reported some residual hydraulic fluid leaking.  Once given the all clear; we were escorted and tugged to the Cessna Service Center.  Total time from landing to completion of tow off the runway was about 50 minutes. Initial post-flight inspection points to a simple burst of a hydraulic line under the aircraft forward of the wheel wells. The only evidence I saw was the spray pattern of residual hydraulic fluid.  I'm surmising it burst during the gear retraction as the gear did begin to rise before free-falling back down. The crew coordination went very smoothly as we divided up our duties to complete checklists; communicate; and coordinate emergency services. We were fortunate to have plenty of time and good weather to determine a course of action; brief it; and execute.  It was also very good to brief and re-brief the exact sequence of our non-normal landing as we had to use emergency braking; back-up steering and non-standard reverse thrust.  A thorough brief along with a mental 'chair fly' of the landing sequence was very helpful.
[Report narrative contained no additional information.]
A C-750 hydraulic line burst after takeoff with EICAS alerts HYD VOLUME LOW A and HYD PTU FAIL. Both red and green gear lights illuminated with the handle UP; so an emergency was declared; the flight diverted to a nearby airport for an uneventful landing; and then was towed off the runway.