Oil, Ingenuity, and Altitude: The Unconventional Save of a CH-47 Chinook & It’s Crew

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(Photo – Paul Marshall; Rear; CW2 Guy Pierce, CW2 Paul Marshall, Front; Rusty Crocker, FE John Guyron, Bill Cradic)
(Photo – Paul Marshall; Rear; CW2 Guy Pierce, CW2 Paul Marshall, Front; Rusty Crocker, FE John Guyron, Bill Cradic)

Emergency procedures—boldfaced, underlined, and ingrained in memory—are crucial for addressing a myriad of atypical situations pilots may face. Yet, the unpredictable nature of aviation emergencies sometimes calls for solutions that extend beyond standard protocols. In 1986, a five-ship formation of CH-47D Chinook helicopters redeploying to Fort Campbell, KY, departed from the former Roosevelt Roads Naval Air Station in Puerto Rico. This first-hand account underscores the importance of out-of-the-box problem-solving and effective leadership under pressure.

A Chinook led the formation carrying a crew of five and equipped with two internal ferry tanks as the fuel needed for the extended overwater trip.  All of the formation aircraft were loaded close to their maximum gross weight of 50,000 lbs.  Approximately 30 minutes into the flight, during a routine “ramp check,” (this inspection occurs in-flight where the CH-47 Flight Engineer positions on the aft ramp to view the aircraft’s Aft Transmission & other vital components) the flight engineer noticed oil leaking from the Aft Transmission area. Upon closer inspection, the source of the leak was identified as a crack in an auxiliary oil pressure switch, leading to rapid oil loss—a dire situation exacerbated by their 50-mile distance from the Puerto Rican coast. At this point, the oil was not dripping but was spraying out so fast and with such volume that by the time the Flight Engineer made his way to the companion way to describe to the pilots what was happening, he appeared to have taken an oil shower. The expression on his face transmitted the degree of absolute peril the aircraft and crew were facing, as he was aware the remaining oil in the transmission’s sump would not last to make it to shore. Normally an immediate emergency landing was in order, but we were hard over the Atlantic. 

(Image courtesy of www.chinook-helicopter.com)
(Image courtesy of www.chinook-helicopter.com)

If you are not familiar with the CH-47 Chinook, the counterrotating main rotor blades must intermesh in a synchronized rotation.  The loss of any of the five transmissions: forward, aft, combining, and two engine nose boxes is catastrophic. Each of these transmissions has its own independent oil lubrication system, which monitors pressure and temperature from the cockpit. This design is crucial for the helicopter’s operation, ensuring that power is efficiently transmitted to turn the rotors for flight.

We declared an emergency and made an immediate turn back towards land.  It would take about 25 minutes to reach the nearest land; Coast Guard Air Station in Aguadilla, on the northwest corner of Puerto Rico.  The maintenance officer in his ship was “flying chase” behind our crippled Chinook and was sharing options over the radio.  With each passing moment, the oil quantity in the aft transmission was getting dangerously low. Along with that, the oil pressure began to slowly decrease as the lifeblood of the transmission was bleeding out.

With the prospect of the transmission running out of oil, leaving us short of landfall by a mere 10 to 15 minutes of flight time, a plan to ditch was discussed. Whenever the pressure went to zero on the gauge, the plan to ditch would be put into action.

Going through my mind . . .Chinooks were designed to safely float within a few parameters. This Chinook at the time was over the max ditching weight and with the current sea state, it was expected to roll over as soon as the blades were too slow in rotation to keep it stable and floating upright. The plan was to slow to a speed just above ETL (Effective Translational Lift), just above the waves, to facilitate all but one of the crew abandoning ship.  I, the PIC, would fly a safe distance from the rest of the crew and put the stricken ship in the water. Faced with the potential of a transmission dry-out and seizure before reaching dry land, the pilots declared an emergency and set a course for the nearest landfall, the Coast Guard Air Station in Aguadilla (TJBQ). As the aircraft’s condition deteriorated, the maintenance officer, flying in formation, began exploring emergency options over the radio.

In the face of an imminent ditching scenario, the crew prepared to abandon the helicopter just above the waves. However, moments before executing this last resort, an innovative solution emerged. The Flight Engineer, recalling a can of engine oil in the cargo bay, proposed using it to service the transmission mid-flight. This quick thinking was met with an immediate and decisive endorsement from the Pilot in Command.

As the Flight Engineer rummaged through the cargo bay, he stumbled upon an unexpected find—an entire case of transmission lubricant mistakenly loaded onto the aircraft the previous day! The crew created an assembly line to source, open and hand the oil to the Flight Engineer, standing on the cargo, to pour the precious oil into the transmission with the driveshaft spinning mere inches from his oil-soaked hands.  Despite the ongoing oil leak, servicing the gearbox with the found lubricant gradually restored the transmission pressure to normal levels. As the last can was poured into the leaking transmission, the aircraft landed safely at US Coast Guard Air Station Borinquen on the Northwest Coast of Puerto Rico.

This incident highlights a remarkable display of leadership, resourcefulness, and teamwork. The enlisted flight crew’s initiative and ingenuity were pivotal in averting a catastrophic outcome. This story serves as a powerful reminder of the importance of adaptability, thorough knowledge of one’s aircraft, and the willingness to “work the problem” with creativity. In aviation, as in life, unconventional means sometimes lead to the most satisfactory outcomes.

Paul Marshall
USMC/Army/USCG Veteran