Cessna Citation Sovereign (C680)
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Time Pressure; Troubleshooting
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Loss Of Aircraft Control
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; Flight Crew Regained Aircraft Control; Flight Crew Overcame Equipment Problem
Aircraft
XA10 LT (Local Time) - First indication of hydraulic problem occurred between waypoints ZZZZZ and ZZZ3 at FL290. 'Hydraulic Pressure Low R' amber CAS (Crew Alerting System) message posted. Quick Reaction Handbook (QRH) checklist was called for and completed. Fault did not clear. Condition was announced with Center but no emergency was declared.XA15 LT - 'Hydraulic Volume Low' then 'Hydraulic Pressure Low L and R' amber CAS messages posted. Autopilot became disengaged and airplane rolled slightly to the right. Altitude loss occurred and [requested priority handling] with Center and descent to FL240 was assigned. Unfamiliar with surrounding airports; we requested clearance to an airport with the longest runway. ATC cleared us to ZZZ. Passengers were informed of the emergency and briefed to remain seated and secured with seat belt and shoulder harness.XA25 LT - After working through the QRH checklist procedures for 'Hydraulic Volume Low' and 'Hydraulic Pressure Low L and R'; I instructed the FO (First Officer) to send an AFIS (Automatic Flight Inspection System) message to '[Fleet Y Dispatch]' by my mistake instead of '[Fleet X Dispatch]'. That was due to memory fallback from coming from the [another] fleet. XA30 LT - Since we were closer to ZZZ1; ATC offered clearance to ZZZ1. We accepted and proceeded to ZZZ1; and descended to 10;000 MSLXA35 LT - After completing the FMS (Flight Management System) landing initialization data for ZZZ and applying the emergency checklist Flaps 35 landing distance 1.63 multiplier; we decided that runway X; with the displacement and landing distance available (LDA) of 7280 feet was unacceptable. We informed Center and requested clearance to ZZZ2. Also requested they inform [the FBO] for towing after landing. During this time we reviewed the QRH checklist again and discussed the failed components as well as the possibility of a fire upon landing. The Evacuation checklist was reviewed as well as individual actions should it become necessary. The box pattern towards ZZZ to ZZZ1 to ZZZ2 gave us time to burn off fuel and reduce the airplane gross weight from takeoff at 30;240 lbs. to approximately 28;000 lbs. upon landing.XA45 LT - Radar vectored for the ILS XXL at 3;600 MSL. Weather at ZZZ2 was VMC; dry runway. Approach checklist completed and emergency checklist actions reviewed again. Airplane was configured early on final due to manual gear extension. When I called for flaps 35; FO selected flaps 35; and the airplane rapidly rolled uncommanded to the right approximately 45-60 degrees and pitched down. FO immediately returned flaps to 15 and I was able to regain aircraft control. Loss of aircraft control and recovery was announced to ATC and flight path for ILS XXL was reestablished. Since there was no published landing multiplier for Flaps 15 in emergency checklist for loss of hydraulics; I doubled the landing distance for wet runway and rounded up to determine that 10;000 ft. would be required with 11;095 LDA. Approached continued with Flaps set to 15. At approximately 1000 ft. AGL; I had FO control the power levers throughout to touchdown and I focused on maintaining aircraft control and runway centerline.XA49 LT - Crew coordinated landing at 15 Flaps Vref and rollout was performed. After touchdown FO maintained forward pressure on the Yoke and I controlled the nosewheel steering with tiller while applying emergency braking. Rollout and complete stop occurred with 1;000 ft. of runway remaining. XA51 LT - Engines off. Crash rescue gave an all clear and FBO personnel hooked up and towed airplane to FBO and parking without incident.XB00 LT - Passengers deplaned. Notification to company about emergency landing.XB05 LT - Post flight revealed hydraulic fluid dripping from right engine drain mast and right wing spoiler panels #7 and #9 extended. No visible damage to main landing gears or airplane was found.XB20 LT - Debriefed passengers on details of hydraulic fluid loss and crew emergency corrective actions. They were somewhat shaken but relieved.XB30 LT - Follow-up telephone conversations with company personnel and maintenance report write-ups.Given the successful outcome of this emergency; it is apparent to me that the flight training [the company] provides contributed to this success. Two pilots that have never met; much less; flown together just one day prior for the first time; was able to coordinate and apply CRM (Crew Resource Management); threat analysis; and emergency procedure execution. FO deserves special recognition on retracting the flaps at a critical moment and his professional duties throughout this event.I feel the 'Hydraulic Pressure Low' and 'Hydraulic Volume Low' QRH checklist needs to be revised. There must to be a 'warning' or 'caution' that states - If uncommanded roll occurs during flap extension; flap handle return to previous position. This may be due to spoiler panels not fully stowed. The spoiler EICAS (Engine Indicating and Crew Alerting System) speedbrake/spoiler display never indicated that the spoiler panels on the right wing were extended. Flight control system description (Flight Safety International Initial Pilot Training Manual) states that 'Loss of hydraulic pressure results in a loss of spoiler control; and the spoiler panels ratchet to a stowed position.' I found nothing that made that statement in the Cessna AFM (Aircraft Flight Manual). Also; there needs to be a landing distance multiplier for less than 35 flaps. Final approach is no place to swag a landing distance requirement when flaps 35 are not available. The only location for landing distance multiplier that would be applicable is in the Cessna AFM for Dual Engine Flameout - 'For flaps 15; multiply flaps 35 landing distance by 1.90.' Luckily we guessed correctly.
Citation Captain reported a hydraulic problem during initial climb forcing them to return to the departure airport.