Setting Conditions for Success
April 2, 2012
On Sept. 9, 2010, we received the call to conduct combat operations in the northeastern mountainous areas of Afghanistan. Over the previous 10 nights, we had conducted operations throughout Afghanistan, so the call for action was not completely unexpected. However, we never expected this night to end the way it did.
We were the lead MH-47G in a flight of three. My co-pilot, Chief Warrant Officer 3 Bryan Young, and I had been flying off and on together for many years and continuously for the last 30 days on this particular rotation. The rest of the pilots in the flight were familiar and comfortable with each other, which made for excellent crew coordination in each aircraft.
We departed our airfield under the cover of darkness with zero illumination. Both Chalks 1 and 2 had about 20 Special Operations Forces personnel on board, putting the aircraft gross weight at 44,500 pounds, while Chalk 3 was carrying a 10-man initial reaction force and a six-man combat search and rescue force. The 20-minute flight would take us to the helicopter landing zone, which was south of our forward staging base in the mountains.
At 10 minutes out, we received updates regarding the enemy position and our particular HLZs. Only Chalks 1 and 2 were infilling tonight, so I directed Chalk 3 to enter into a holding pattern should any contingencies develop.
Seven minutes had gone by and all seemed normal until we received intelligence updates indicating we had one enemy combatant moving away from the primary target area. This is not an abnormal occurrence, but it requires effective coordinated communication with the lead cockpit for command and control. The ground force commander, air mission commander and I all communicated with each other, ensuring information was conveyed throughout the battle space. Since the enemy combatant did not come out of the primary target building and was moving away from the two infil HLZs, the ground commander and I ultimately saw no reason to deviate from the primary plan.
While all of this communication was going on, Bryan was waiting patiently to ask me one simple question, "Did you touch the flight controls?" Around the same time, we had enemy movement and Bryan had felt an abnormal vibration in the flight control system. It had only lasted a second and felt as if the pilot not on the controls had accidentally bumped them. I responded to him that I had not, yet we both knew it was possible I did. While in a blacked-out cockpit and under night vision goggles, I attempted to spot the HLZ, communicating over the radio and bending forward to enter mission data into the aircraft's avionics suite. I could have easily bumped the controls while doing this, so we went back to focusing on the mission.
The infil went as planned. The HLZs for the flight were long, thin spurs that made up the foothills of the 14,000-foot mountain range and flowed into the valley floor, creating deep ravines as they continued to the river to the north. After infil, we began to egress on the planned route and took enemy fire from the target area as we cleared the dust cloud. This caused us to deviate from our planned route and continue parallel to the mountain range. The evasive maneuver put us low and fast, flying 150 feet above ground level at120 knots.
Once again, I heard Bryan ask, "Steve, did you hit the flight controls?" over the internal communications system. This time I was sure I hadn't and announced, "Left seat inside," ensuring Bryan and the four crewmembers in the back picked up my scan outside for airspace avoidance. Using a small finger light, I began to look around the flight controls to make certain nothing was interfering with them. I didn't see any problems, so I took over the flight controls from Bryan and asked him to do the same on his side of the cockpit. At first, the flight controls felt normal, and then I felt what Bryan had been asking about.
In less than a second, the aircraft cyclic violently shook left and right about an inch. This happened so fast that the aircraft's integrated hydraulic/mechanical controls didn't have time to take the inputs from the cyclic and input them into the rotors. Also, the thrust of the aircraft pulsated up and down, but not as violently.
We were still evading enemy fire, flying about 150 feet AGL at 100 knots. I began maneuvering away from the ridge paralleling us on our right. As I turned, the flight controls hit a stop. I had about an inch of play in the pitch, roll and thrust axis of the aircraft. I immediately rolled level and attempted to set up for a landing, asking Bryan to get back on the flight controls with me. As he did, he understood how dire our situation was becoming.
About the same time, the aircraft hydraulics froze. We were in about 5-degree nose-high attitude descending at 100 feet-per-minute. The only problem was there was no place to land. Beneath us were 150-foot deep ravines with bottoms too narrow to fit a Chinook. I left Bryan on the controls as I began the emergency procedure for a dual hydraulic flight control failure.
We had not received any warnings or cautions on our instrumentation nor did the crewmembers in the back have any indications on their maintenance panel identifying a hydraulic failure. I recalled the aircraft operator's manual stating, "If both hydraulic systems fail, flight controls cannot be moved." I immediately concluded we had a dual flight control hydraulic failure. Although I completed the emergency procedures, the flight controls remained locked.
I returned the controls to Bryan, hoping he might be able to regain some level of control, but that proved futile. The aircraft was in its final attitude and nothing Bryan or I did was going to change that. We continued to pull and push the cyclic with both hands in an attempt to maneuver the aircraft to a suitable landing area. The crewmembers in the back began to call out possible landing sites, not knowing it was impossible for us to slow the aircraft to maneuver to them.
The deep ravines began to turn into rolling hills, all too steep to attempt a roll-on landing. Then at the two o'clock position, Bryan noticed an opening in the hills that led to a dry riverbed. He announced this to me and we attempted to maneuver the aircraft, but, yet again, the cyclic would not move.
Our minds raced and then I realized the only control axis we had not attempted was the yaw axis. This is done by adjusting the flight controls that are mechanically linked to the Chinook's pedals. I pushed the right pedal to maneuver the aircraft to the two o'clock position, but the pedal would not move. I tried again, this time pushing on the right pedal with both feet as I braced my back against the aircraft seat and used the cyclic for better leverage.
Bryan was still attempting to manipulate the other flight controls as the aircraft's attitude began to change, also changing the aircraft's aerodynamic state. The riverbed came into the 12 o'clock position as the hill we were heading for passed out the left-hand side. Once I released the pressure on the pedal, the aircraft continued forward. We were now at 30 feet AGL and 50 knots and still descending.
The aircraft touched down in the riverbed at 45 knots with a 5-degree nose-high attitude. As the aft wheels touched, both Bryan and I pushed down on the thrust as hard as we could in an attempt to change the dynamics of the rotor system and keep the aircraft on the ground. The aft wheels dug into the loose sand, burying them up to the aircraft frame. We rolled for about 75 feet before the aircraft brutally stopped, throwing us forward. The whole event, from the controls freezing to the aircraft coming to rest, lasted between 45 and 60 seconds.
Not knowing whether enemy fire had anything to do with the hydraulic failure, I quickly conducted an emergency engine shutdown and we began egress procedures. The exact distance from the enemy was unknown to us. After ensuring none of the crew was hurt, we began to establish a 360-degree security of the area. I made contact with our other aircraft using my survival radio and, within minutes, the initial reaction force and combat search and rescue teams were on the ground to assist. Thirty minutes later, our internal downed aircraft recovery team launched from our airfield and was on site for recovery.
We discovered later that four times the allowable amount of water had gotten into the flight control hydraulic fluid system. Water has a lower boiling point than hydraulic fluid and, at some point during the flight, the water vaporized, causing the hydraulic system to cavitate.
Good crew coordination was an important part to the successful outcome of the emergency procedure. However, battle rostering played just as large of a role. Bryan and I have had years of aircrew coordination training and understand how important this is in the Chinook community, especially with a crew of six. The fact remains if that was our first flight together, the outcome may have been different. The benefit of battle rostering crews (for short durations) allowed for more effective crew coordination.