By Don Mathis, Kinetic Social CEO
Last week, I began a post on how the OODA loop – Observe, Orient, Decide, Act! – played out in an emergency situation faced by my P-3 Orion patrol squadron aircrew. We were over the North Atlantic on a Search & Rescue (SAR) mission, and the irony that we might be the ones needing rescue was not lost on us.
The point at which I broke off the narrative was just as we were pulling out from a dive towards the thundering waves below us. Fighting asymmetric thrust, we had lost an engine at low altitude on the same side of the wing where another engine was already shut down. We were yawing left while in a steeply banked turn, near – or even slightly below – minimum controllable airspeed.
In the moments after we recovered from our fall dive towards the sea, the pilots got engine #1 going, gained altitude, and secured the malfunctioning #2 engine. We all breathed a serious sigh of relief. I remember looking out the bubble window just aft of the flight deck, watching for the now shut-down engine number #2 propeller to wind down to a stop.
But it never did. The enormous four-bladed Hamilton Standard propeller kept on rotating. The plane shuddered with vibrations. The flight deck could not get the prop to “feather”. Feathering is when the prop blades are halted and angled into the wind to reduce drag after shutting down an engine.
There is an old saying among crusty senior Orion Flight Engineers: There are only two things on a P-3 that will kill you and they both start with P: Pilots and Propellers.
The flight deck crew executed all of the emergency procedures outlined in the manual in their attempt to feather the prop. Nothing worked. The propeller RPMs slowly increased as the plane’s very forward motion through the air caused the prop to speed up in its rotation.
So now, with the prop wind-milling freely, we faced the risk of a propeller overspeed. It is one of the most dangerous situations on a turboprop aircraft:
- There is a chance that centrifugal force will wrench the 1,200 pound prop right off the aircraft, which could slice through the fuselage and / or lead to an out-of-control plunge … both catastrophic scenarios.
- Equally concerning, an overspeeding propeller decoupled from the engine’s reduction gear box could lead to a fire. Not a good thing when that engine is attached to a wing with thousands of pounds of fuel. Attached to an aircraft with 10 souls on board.
Without getting too technical, we later learned that the reduction gear box – the component that, in rough terms, connects the engine to the propeller – had experienced a catastrophic failure. It “fodded out” other key components of engine #2. “F.O.D.” is an aviation acronym for Foreign Object Damage; when the reduction gear box failed, it sprayed metal parts at high velocity throughout the engine.
There have been several accidents – in the Navy we call them “mishaps”, in typical military understatement – under very similar circumstances to the ones we now found ourselves in. In 1987, A P-3 in Hawaii faced a prop overspeed that, after two hours of flight time home, eventually led to the propeller separating from the aircraft. The prop took out the engine next to it and nearly led to the loss of the aircraft as it was on final approach.
Worse, a P-3 out of Adak, Alaska had a very similar situation, ending with disastrous results. In that case, the overspeed condition eventually caused a fire. The crew discharged the engine fire extinguishers; it caused a fire again, they extinguished it again; when the overspeed led to a third fire and their extinguishing agent was exhausted, the crew was forced to ditch the aircraft in the heavy Alaskan seas. Five members of the crew perished including the patrol plane commander. He had stayed atop the aircraft after escaping through the cockpit roof hatch before the plane sank, counting his crew to ensure all got out of the plane. He was swept away by the waves after that.
In our case, the crew had to carefully walk through the OODA Loop in this crisis. First, where should we go? We were pretty much in the middle of the North Atlantic; St. Johns, Newfoundland was the nearest land. So we headed there, still several hundred miles away and on the other side of the ocean from where we’d started our flight that day. The P-3 that lost the prop off of Hawaii flew for about two hours before its overspeed condition led to near disaster; the aircraft off Alaska, less than that. It would take almost three hours to fly to St. Johns. We all knew the history of these other flights.
Should we plot our course near identified ships, in case we needed to ditch? (We were far, far outside of helicopter rescue range). But if we did this, we’d add minutes or more to the flight, which could have fatal results. We decided to fly straight to St. Johns.
How fast should we fly? A trade-off between precious time versus the risk of the faster slipstream possibly speeding up the runaway prop. We opted for operating the aircraft at as slow a speed as practical while maintaining at least some margin of safety above minimum controllable airspeed (see my prior post about the P-3 that stalled and spun when they got below minimum controllable airspeed). It was a painfully slow speed, prolonging our flight over the crashing seas to a safe haven.
Should we prepare for ditching or for bail-out? This was an easier one… no one really thought jumping out of the plane in parachutes over the ranging North Atlantic was a good idea … even if we survived getting out of the plane, the odds of finding us in the seas below were slim-to-none.
Each question led to more questions, each decision led to action after observing the developing situation and orienting to it.
The next several hours were the longest many of us would ever experience. The crew was mostly silent and nervous. I recall sitting at my station, warily watching the very big, violent ocean below, going over and over my emergency ditching and egress procedures in my mind, and dwelling on the low odds of surviving a ditching so far from rescue.
My communications duties included telling everyone I could about our situation and our location after we’d declared an emergency. We communicated with SAR resources, our Navy command, other aircraft, and oceanic air traffic control out of Gander, Newfoundland. Over the Atlantic, there is no radar tracking; you call your position to controllers who monitor your progress. I’ll never forget hearing the concern in the controller’s voice; he was professional, but you could tell he thought he might be the last person to speak with us alive.
During the course of the flight, we regularly experienced jarring and unnatural vibrations originating in the engine, as critical components continued to disintegrate. We briefed emergency procedures for ditching and for fighting an engine fire if it broke out. And we watched that big #2 propeller going round and round, wondering when it would speed up fast enough to cause a disaster.
At one point, an officer suggested we fly another thirty minutes past St. Johns, a civil airfield, because of all the top secret crypto gear on the aircraft. There was a Canadian military base where our equipment and codes would be more secure, he reasoned. If looks could kill, he’d have been dead on the spot.
Eventually, we made it to St. Johns and landed safely on three engines. We’d never been so thrilled to be back on terra firma. In an expression that I heard one of our sensor operators use, we spent that long, long flight “puckered up tight enough that a team of horses couldn’t pull a greased knitting needle out of our arses”. But we made it.
In a future post, I will discuss the OODA implications of all this. Stay tuned!
This post is dedicated to the brave men and women of the Navy Patrol Squadron community past & present, and especially to those who have lost their lives while being ever vigilant in defense of our nation.
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Don Mathis is the CEO and Co-Founder of Kinetic Social, a social data and technology company focused on making sense of the world’s social signal. He also serves in the US Navy on reserve duty, where he is an Expeditionary Combat Logistics & Anti-Terrorism Officer.