When a disaster such as an airline crash happens, investigators usually can piece together a whole chain of events that led to the accident.
The full investigation is not yet complete, but in the case of US Airways Flight 1549 that chain appears pretty short: Canada geese ingested into both engines of the Airbus A320 caused the plane to lose power shortly after take-off and necessitated a “splash landing” in the Hudson River.
On the flip side, those aboard the aircraft had a number of factors working in their favor. By all accounts, the training of both the flight crew and the cabin crew paid off, enabling Capt. Chesley B. “Sully” Sullenberger to coolly steer the jetliner to a soft splash landing on Jan. 15.
Then there’s pure luck. As a result of the smooth landing, there was no break-up and no fire. The plane’s 155 passengers and crew evacuated relatively calmly and were quickly surrounded by rescue craft.
But there are also the plane’s backup systems, which apparently performed as designed to provide power that allowed Sullenberger to maintain control of the aircraft. Crash investigations determined that 1549’s ram air turbine (RAT)—essentially a small propeller that drops out of the bottom of the plane to drive a hydraulic pump and provide backup power to help operate the plane’s flight controls—was deployed before the touchdown.
The story of the RAT and the aircraft’s auxiliary power system not only illustrates the complexity of aerospace supply chains, it also highlights the importance of the right finish in ensuring that a product functions as intended.
The tale begins with a solenoid produced by G.W. Lisk Co. Inc., a Clifton Springs, NY manufacturer of solenoids, valves and other components for aerospace and industrial applications. Lisk manufactures standard solenoids rated to withstand more than a million cycles in service. In the case of Flight 1549, its part number L-6810 solenoid only had to function once.
According to company president Mark Kowalski, the two-pound steel component energized and released a locking pin that allowed the RAT, supplied by G.W. Lisk customer Arkwin Industries of Westbury, NY, to deploy. The RAT, in turn, powered an auxiliary power system supplied by Honeywell International Inc. (Morristown, NJ) that enabled Sullenberger to steer the craft to a soft landing.
Helping to ensure the solenoid functioned as intended were electroless nickel deposits on the device’s critical inner workings. The solenoid’s plunger and shaft were EN-plated to provide corrosion protection and lubricity, according to plating process supplier Enthone.
The finish did its job, enabling the solenoid to function flawlessly during the nine-year-old aircraft’s emergency.
“You never want to have to use the solenoid, but when you do, it has to work perfectly,” Kowalski says.
Amen to that. And cheers to all the manufacturers in the RAT supply chain for their part in the “miracle on the Hudson.”