On the way to Super Bowl 52 – Hydraulic failure in the Cessna Citation CJ2

Off  to the Super Bowl

A friend asked me to fly the Cessna Citation CJ2 to the Super Bowl in Minneapolis while he was on a well deserved vacation.  It sounded like a good idea, I always enjoy flying into  busy airspace and events and it is a refreshing challenge coordinating all of the components and seeing so many aircraft in the air at the same time.

It started out as a perfect flight, flying the  CJ2 cross country from San Diego (KCRQ) to Minneapolis St. Paul (KSTP)  for Super Bowl 52!  Our support team, who manages the aircraft, did an amazing job arranging the ground details including coveted hotel rooms on short notice.

We were able to get an arrival slot and parking — one of 235 reservations  at Signature alone. and a total of 1200 aircraft operations in the area. After a stop in Van Nuys (KVNY) to pick up a passenger, and get our warm clothes ready for the cold we were off to Minnesota.

Starting off on our Super Bowl adventure - in a warm climate
Starting off on our Super Bowl adventure – in a warm climate

  we did a fast turn at Scottsbluff Nebraska (KBFF).  The fueler at Valley Airways, the FBO at  KBFF, was great, providing us with a very quick turnaround and and very reasonable fuel price.  Overhead we saw a flock of birds heading north, which seemed a bit early for February.

Valley Airways Scottsbluff NE KBFF - Birds Flying North Overhead
Valley Airways Scottsbluff NE KBFF – Birds Flying North Overhead

 

We could have made it non-stop to KSTP if everything was perfect, including weather and traffic, however my experience flying into other high volume events, such as EAA , a  stop is the safest option.  I’ve been on final approach at Oshkosh (KOSH) and the aircraft in front of us had an incident on the runway, requiring us to go missed, enter holding, and eventually land elsewhere.

The flight was great.  I took the opportunity to teach my co-pilot, Perry, some additional functions of our Universal Flight Management System (FMS) as we flew across the US at FL390.  While not the latest system, it worked well especially when coupled with the Garmin GNS530 and our Rockwell Collins Pro Line displays.

CJ2 Universal FMS
CJ2 Universal FMS

The outside temperatures were cold on this flight so it was easy to fly at that altitude in the CJ2 and it provided a slight speed advantage over flying at FL410 or above.  We encountered some clouds, and a little ice on the descent however it was extremely smooth, and fun as usual!

Super Bowl Arrival

We were cleared into KSTP via the GOPHER 1 Arrival   with the expected altitudes.  Everything was going by our plan. Perry and I remarked how we fit in nicely into the flow into Minneapolis for the Super Bowl and while others had to hold, we were flying directly to the approach corridor. Other than anticipating weather that was 80 degrees colder than San Diego, we were set.

Arriving into the Minneapolis area. Heavy traffic on the arrival. A lot of football fans!
Arriving into the Minneapolis area. Heavy traffic on the arrival. A lot of football fans!

I arrived on base leg on the ILS 32 at exactly our arrival time slot, 1604 MST, which was probably a fluke, but useful in any case!  This was the only runway open and was covered with snow and some ice, with a moderate crosswind, thankfully the freezing fog had left an hour ago. The other runways, along with all ramp areas, were  snow covered,  used for parking the large number of airplanes. It looked like one large snow field!

Remember – Fly the Airplane!

The ILS approach proceeded well, Perry was doing a great job monitoring our progress and did the callout at 500 feet AGL with a confirmation that the annunciator panel was clear, gear down, and runway 32 confirmed . Out of the corner of my eye I saw the hydraulic advisory light flicker ‘HYD PRESS ON’ which is not usual when the system pressurizes as you activate the systems, such as flaps, speed brakes, or gear which are electrically controlled but hydraulic actuated.

Upon landing we put out the speed brakes and the Hydraulic Low Flow Warning  (HYD FLOW LOW L R ) lights flashed quickly, then went solid – on both engines. Not a good sign.

Low Hydraulic Flow Annunciator
Low Hydraulic Flow Annunciator

When both of these annunciators illuminate it can only mean one thing – we lost all of our hydraulic fluid. We still had a ways to slow down the aircraft on a very slippery runway with a right crosswind and since the brakes are on a different system they would not be affected.  The most important operation for a pilot is to always fly the airplane. If you allow yourself to become get distracted at critical times, it doesn’t always work out well. 

I elected to taxi off the runway and park the plane. At this point I  didn’t want to block landing traffic, nor did I want to quickly shut down the engines without a proper cool down. The hydraulic pumps were probably already damaged however, if you shut down a jet engine too quickly you risk blade rub on the case and other issues. While shutting down the engines quickly with a hydraulic failure might save the pumps, however there are no guarantees they would be okay – especially when both lights were illuminated.

KSTP Ramp - Maybe I need a snow machine instead of an airplane.
KSTP Ramp – Maybe I need a snow machine instead of an airplane.

While I secured the plane Perry helped the passengers deplane in very cold weather and mentioned I may want to take a look at something that the line person noticed —- not yellow snow but orange!!! The left wing was partially covered in fluid by the speed brake, and unless I hit a Yeti on landing it was hydraulic fluid!

We may have a slight problem with the left wing. Hydraulic fluid leaking from actuator.
We may have a slight problem with the left wing. Hydraulic fluid leaking from actuator.

The left actuator had actually burst at the seams and virtually emptied the hydraulic reservoir onto the beautiful Minnesota snow – on Super Bowl eve at one of the busiest airports in the country that night. After ensuring our passengers were in the warm shuttle to the Signature FBO on the west site of the airport, we post flighted the aircraft and started working on a plan. We had made it to the Super Bowl and we could deal with it, we just didn’t know how at that time.

Remind me - Why did we leave San Diego?
Remind me – Why did we leave San Diego?

Upon entering Signature shivering a bit from the cold, the Super Bowl Host Committee greeted us with mittens and hats, a great indicator of hospitality, and warmth. Over the next few days we would visit them often.

Gifts from the Super Bowl Welcome Committee - very appropriate
Gifts from the Super Bowl Welcome Committee – very appropriate

I inquired if Signature had a maintenance facility, which they did – TechnicAir. Things were looking up. I was put in touch with Bill Wuorinen , the maintenance supervisor at TechnicAir and explained our situation. I knew I was asking the impossible – significant maintenance help on the Saturday night before Super Bowl, below zero temperatures at night, with no hangars available and a number of other pilots needing help. Within 15 minutes we had a plan – Bill graciously agreed to help me diagnose the problem and move one of their planes out of the hangar.

Bill and I moved the plane to their shop. It was now almost 7pm and one of Bill’s staff started work on it immediately and removed the burst actuator from the left wing. The fluid pressure in the system is approximately 1500PSI and it appeared the bolt heads had sheared which meant that fluid at extremely high pressure exited the system immediately upon activation of the speed brakes.

Speed Brake Hydraulic Actuator - sheared bolts and split open
Speed Brake Hydraulic Actuator – sheared bolts and split open

The Textron Mobile Service Unit (MSU) was unable to help for at least three days, so it was gracious of Bill to help.  The actuator was ordered just before 10 pm for delivery the next day and we hadn’t confirmed the status of the pumps; that would need to wait until the morning. In retrospect it probably would have been a good idea to order new pumps at that time as well.

Super Bowl – Downtown Excitement

I elected to explore Minneapolis to see the excitement for Super Bowl. It was crazy downtown. After walking around, seeing if I could still avoid frostbite, I found a great small place off the beaten path with a DJ, Lyon’s Pub.  I appeared to be the only non-local which meant it was a great local bar.  I could tell I was in Minnesota since people were wearing knit hats and boots on the dance floor ! If you visit Minneapolis I highly recommend a visit to Lyons Pub, for drinks o music. Everyone was excited about the game and it was fun talking to folks about their predictions.

Lyons Pub - Minneapolis, a great local pub and DJ
Lyons Pub – Minneapolis, a great local pub and DJ
The Super Bowl Clock countdown - only 17 hours to go!
The Super Bowl Clock countdown – only 17 hours to go!

Bill kept me advised late into the night on the part delivery tracking and we both hoped our problem would be solved quickly. Little did we know that in the morning we would find the hydraulic pumps were also damaged.

New Day – New Parts

In the morning they removed the hydraulic filters and found what appears to debris from the hydraulic pump. New pumps and filters were required, and ordered. Another delay, and now we were trying to get the parts delivered same day during Super Bowl. I have to give credit to the Textron delivery process, they had the pumps on a flight to MSP to arrive on a United flight at 11:30pm. The problem now was United airlines wouldn’t release the part to us until the next morning, not exactly the best customer service for AOG.

Hydraulic Fluid Filter with debris in the pleats
Hydraulic Fluid Filter with debris in the pleats

Early the next morning the technicians noticed that one of the replacement pumps arrived damaged from Textron. Our significant delay was expanding even more. I had two passengers that had critical meetings on Monday and a broken bird. As Captain I take responsibility for both my passengers and aircraft, so now it was off to find alternative transportation.  There were no commercial flights within four hours of driving distance due to the Super Bowl, so we worked on a charter option.  The problem was there were no arrival slots, even if we could find a plane to charter.   While a colleague searched for charter options, I negotiated for arrival, and the subsequent departure, slots.  The staffs at Signature at KSTP and Lynx at KANE were incredibly helpful in arranging the slots we needed.

After additional work by TechnicAir the plane was back in service on Tuesday. In light of the situation the down time was relatively little, however it was accomplished by a great team effort of all the aviation professionals in Minnesota and Textron.

The Hydraulic System

The Cessna Citation CJ2 utilizes two separate hydraulic systems, one for the brakes, and another one that operates the speed brakes, flaps, and gear. The brake hydraulic system is ‘closed-center’, while the later system is ‘open-center’.  An ‘open center’ does not operate at high pressure until a sub system is activated, the fluid simply circulates. When the pilot selects an associated flight control device such as the speed brakes or flaps, pressure valves close which builds system pressure to 1500PSI.  Then high pressure hydraulic fluid is routed through the appropriate actuator to operate the sub-system.  In our case, when I extended the speed brakes, a valve closed routing 1500 PSI hydraulic fluid to the actuators.  The left actuator then burst, sending high pressure fluid out of the system.   The reservoir holds 156 cubic inches (2.7QTs) of fluid, so fluid would quickly exit the system.

The hydraulic pumps are mounted on the engine accessory gearbox where a number of ancillary equipment are located including the oil pump, Fuel Distribution Unit (FDU) and the PMA alternator. Of course when the hydraulic fails you lose your speed brakes, flaps, and normal gear extension.

Hydraulic Pump - Foreground
Hydraulic Pump on the accessory gearbox – Foreground

When the system is breached, such as our actuator bursting, the fluid can quickly exit the system. Once the hydraulic pumps run dry the impeller is no longer lubricated by the fluid which  starts the processes of destruction. Once the friction reaches a critical point the pumps fail and in theory the pump drives shears in order to minimize any damage to the accessory case.  Im our situation, the pumps were still operating and the drive shaft was intact. If the pump fails completely then it also sheds material inside the housing necessitating replacement of carbon seals within the gearbox.

If you lose one hydraulic pump, the hydraulic systems may continue to operate unless there is a loss of fluid as in our case.  If you lose both, then you are in a different situation.  If a pilot has complete hydraulic failure of this system, then you are faced with no flaps, no speed brakes, and emergency extension (but not retraction) of the landing gear.  This translates into longer runway requirements and slightly more complicated speed control.  If the runway is contaminated (wet, snow, ice, etc.) then it further complicates landings due to additional runway required for landing.

I’ve reviewed the incident many times,  as the pilot and as a Flight Instructor, analyzing the best procedures.  The established aircraft checklist can only provide guidance under a certain set of circumstances, and are not designed to provide steps for all scenarios.  The checklist only has one option – Land as soon as practical’ – well I had done that so in theory I was successful.

CJ2 Abnormal Checklist - Dual Hydraulic Failure
CJ2 Abnormal Checklist – Dual Hydraulic Failure

My main focus was to ‘fly the airplane’ and ensure the safety of my passengers as the primary goal, with the secondary goal to minimize damage to the airplane systems.  If I had shut down the engines immediately upon low hydraulic pressure I may saved the hydraulic pumps however  we would have faced additional issues including loss of braking, potential engine damage, etc.

Despite the issues with this incident, I was pleased my passengers had a great time visiting a wonderful city and viewing one of the best Super Bowls – Go Eagles!