Making Button-holes

[UpperDeck]

Just read this account of a ride into a storm in the North Atlantic;

After a successful 4-hour flight, the aircraft dropped its final dropsonde, and turned north to complete its final sampling run. Suddenly, crew members observed flames coming from the #3 engine, accompanied by an audible popping sound. "Fire on #3, flames, flames, flames!" came the cry over the on-board intercom system. The pilots and flight engineers immediately began an emergency shut down of the #3 engine. As they worked to shut down the engine, the ominous call, "Fire on #4!" came over the intercom. The pilot immediately began an emergency shut down of the #4 engine. With both engines on the right wing now shut down, the pilot cautiously ramped up power on the two engines on the left wing, turned the aircraft towards home base in St. Johns, Newfoundland, and attempted to climb. However, the aircraft was not able to climb on just two engines, and the pilot was forced to begin a gradual descent to 2600 feet. The pilot notified the crew to review their ditching placards, and word was send to air traffic control informing them of the emergency. Three tense minutes passed, as the crew attempted to figure out what had caused the multiple engine failures. Speculation centered on the unusually heavy accumulation of salt on the aircraft--but excessive salt had never been implicated in engine failures before. Then, the words they all dreaded, "Fire on #1!" burst out over the intercom. The flight engineer immediately pulled the emergency shutdown handle for the #1 engine, and Kermit began a 700 foot per minute descent towards the turbulent sea below.

The crew donned survival suits as the pilot issued a May-day distress call and prepared to ditch the aircraft. Beneath them, hurricane force winds blew over the night-shrouded North Atlantic waters. With waves easily reaching 20 feet, water temperatures near freezing, and 500 miles out at sea at night, prospects for survival were dim. Four minutes remained to restart one of the flamed-out engines, and the pilot called for an immediate restart of the #1 engine. As the flight engineer worked to comply, Kermit passed through a brief rain shower that washed considerable salt from the aircraft. The attempt to restart the #1 engine succeeded, and Kermit pulled out of its descent just 800 feet above the waves--one minute from impact.

The crew now worked to restart the failed #3 and #4 engines, while the plane slowly climbed away from the ocean surface. As they headed towards Newfoundland, the Canadian Air Force launched a search and rescue C-130 aircraft from Nova Scotia to intercept Kermit. Crews on the Hibernia and Terra Nova oil rigs located east of Newfoundland were alerted of the emergency, and stood by to help if necessary. Kermit's navigator continuously plotted vectors to the oil rigs at they flew home, in case a ditch near one of the rigs became necessary.

As they continued westward, the crew successfully restarted both the #3 and #4 engines, but at reduced power. Kermit climbed to a more comfortable altitude of 14,000 feet and made it uneventfully back to St. Johns. Fortunately, the engines were undamaged and perfectly operational after the salt was washed out, and the data collected during the mission was saved. According to the detailed NOAA Mishap Investigation Report posted on Chris Mooney's excellent blog, "Post flight inspection of engines revealed significant white build up on intakes, first stage compressors, and CIP probes of all four engines. Subjectively, the #2 engine appeared to be the worst coated of all engines. Aircraft fuselage and windows were also heavily coated." Salt build-up on the engines was determined to be the cause of the incident. The unusually dry nature of the storm prevented the salt from being washed off, and was probably part of the reason the engines failed on this flight, and not on previous flights.

I asked Dr. Jim McFadden, project manager of the Ocean Winds project, what happened. He was on the flight, and responded:

This event stumped everyone including the experts who spend a life-time studying sea salt and aerosols in the marine boundary layer. Six previous flights in similar conditions had resulted in nothing like this. But this one was different. It was flown over an ocean warmed by the Gulf Stream in a dry slot of cold Canadian air. Somehow that combination was the key to what could have been a disastrous flight. Fortunately, quick thinking and the flawless action of the crew brought about by excellent training got us home safely.