Friday, March 10, 2017

Replacing the world's biggest jet engine ... at -40°

Last month I reported that a Swissair flight had to land in the Canadian Arctic with an engine problem.  The aircraft, a Boeing 777, had to have an engine replaced before it could proceed.

Now Popular Mechanics has published a detailed article on what the engine swap involved, including a number of interesting photographs.  Here's a snippet.

The SWISS team handled the prep-work and readied systems for the engine swap, but GE performed the actual change. Both would rely on support from the local airline (First Air), the fixed base operator, and the Royal Canadian Mounted Police (RCMP), who made their hangar available. None of the groups had met previously, but they gelled immediately.

"I was astonished how fast the team was established," Althammer says. Althammer was one of a trio of SWISS technicians working directly on the aircraft. "You could feel each and every one's passion for aviation and that bound us together."

The combined team would need that passion in order to brave the elements. "There was a constant wind that made the whole thing feel even colder," Rüttimann told Blick im Abend. Without wind, -22 degrees is bearable but working unprotected in these conditions... was not worth thinking about."

The inflatable tent brought along by GE proved to be a lifesaver. Generators and lighting provided by the Iqaluit community raised the tent's inside temperature to a relatively balmy 50 degrees and permitted work during the 19-hour-long February nights. Anyone or anything that ventured outside had to be kept from freezing.

There's more at the link, including a number of photographs showing how the work was done.  Recommended reading, particularly for aviation enthusiasts.

Looks like it was a pretty tough job.  Kudos to all concerned - and a tip o' the hat to reader C. R. for sending me the link to the article.



Anonymous said...

Couple things: I wonder if someone at GE might be thinking about procuring a C-17 as the USAF retires them (which assumes the 17 is big enough to carry a GE90-115).

And, the article didn't mention it, but Im sure there was some discussion about the possibility of flying the 777 out, empty, with a light fuel load, to a more hospitable environment to perform the engine swap. I'd be curious to know the reasons for vetoing it.


David Lang said...

USAF retiring C-17s?

I would not expect them to be available on the surplus market. The USAF is still flying transports/tankers from the '50s, the C-17s are FAR newer than a lot of their transports (the newest generation of transports IIRC). As they shrink reserve units, they may mothball some aircraft, but they are not going to sell them off as they need to be able to reactivate them or cannibalize them to keep the rest of the fleet flying

Anonymous said...

Art, the nearest airport with a suitable hangar is 1,500 miles to the south. That's a long lonely stretch and the prospect of the crew surviving should the other engine fail is pretty low.

If you have an unserviceable aircraft that cannot be fixed where it is you can apply for a ferry permit from Transport Canada, which will stipulate that no paying passengers or cargo and only minimal crew are aboard, and the flight must be in daylight and perfect weather. I've seen airplanes ferried with (slightly) bent wings, broken windshields, the landing gear fixed in the down position, etc but there is no way that TC will issue such a permit if half your engines are not working. I would also guess that the insurance company would tell you to suck eggs if you tried to make a claim should the aircraft fail to arrive.

Could a takeoff be made on one engine? I don't think so. Starting from 0mph and applying 125,000lbs of thrust from #2 engine the plane would yaw uncontrollably to the left. Since there is no airflow over the rudder it is useless to you. In a 'normal' takeoff where an engine fails on the roll, once you've reached V1 there is enough airflow over the rudder to steer the airplane.

I've taxied small jets and one of the things you have to watch out for is turning the nose wheel(s) too sharply under power, usually you use reverse thrust on the side you're turning to and a little positive thrust on the other side as you turn the tiller. If you turn into an engine producing thrust it is possible to roll the nose wheel tires right off the rims.


Anonymous said...

To Anonymous: I would think the reasoning (off the top of my head) for not flying the aircraft out with a light load and one engine, might have something to do with the length of the runway. Half the power and a short runway and you're not getting in the air with an aircraft this large. Just my thoughts.

Anonymous said...

Al has it right.

With a two engine aircraft, you can fail one engine and have one still work (that is how they ended up in YFB in the first place). With only one engine, you have no redundancy at all, and an EFTO (Engine failure at takeoff) would be invariably fatal.

I am an airline flight dispatcher and I have flight planned a "1EO" (One Engine INOP) ferry several times on a Transport Canada Ferry Permit, but that was with a 727, which has three engines. So we were taking off with two out of three engines operating, so with no payload and minimal crew we would still be able to maintain flight with one engine.

Even then, only a limited number of our Captains were trained and certified to do so. Only three or four engined aircraft could get permission to do a "one engine INOP ferry".


Paul from Canada

Old NFO said...

Heh, they at least had a 'tent'... We did work on a P-3 in Thule in 1989 using a parachute and heater. It 'worked' to the point that it was above freezing (quite an accomplishment, considering the ambient was -60F.