Engine test creates big $$$ hole
Seems the exhaust from a KC-46A jet runs about 1170 degrees Fahrenheit, Fairbanks (AK) International airport can attest to this.
Last summer a KC-46A reported problems after refueling, and landed at the Fairbanks airport after the crew reported “unusual engine vibrations” during flight.
The vibrations were severe enough that the jet could not fly, and a special team of maintenance experts was dispatched from McConnell Air Force Base, Kansas, arriving two days later. The crew waited two more days for favorable weather to begin work on the engines.
In each of the 10 engine tests, the report said, maintenance specialists ran both of the plane’s engines at up to 83% power for between 20 and 30 minutes. Each test evaluated a single engine, the report said, but crews run both during tests to avoid damaging the plane with unequal, or non-symmetric, force from only one side.
I can see that – you can assume that having a tied-down plane running an engine at high power would stress the airframe more than flying on one engine, right?
The tests ran the engines at the same power levels used during take-offs, according to investigators, during which the engines produce exhaust at “approximately 1,170 degrees Fahrenheit. The high temperature of an operating engine can be felt more than one hundred feet behind the exhaust.”
The repeated tests, investigators found, created “persistent high temperatures in combination with repeated high engine exhaust” that melted the sealant used on the asphalt.
During the tenth test, a slab of concrete approximately 25-feet by 25-feet lifted off from behind the plane’s right engine, tumbling backwards and shattering across an area roughly two-thirds of an acre behind the plane. Task and Purpose
Looking at the pics linked I think we can assume “concrete” is a misnomer, as it looks like asphalt (sorry, couldn’t link the actual correct photo.) But a 25 foot square crater where planes go just doesn’t sound like an ideal condition. 10 high speed runs duplicating takeoffs for each engine works out to about 10 hours of high temps you can feel 100 yards away
Not quite $150 large to fix, too – $147,044 to repair it. Yowzas, that’s a pricey pothole.
The investigation’s report attributes no fault to the plane’s pilot/crew (who weren’t present during the testing anyway) or to the maintenance guys. One suspects guidance may be issued in future suggesting that combining asphalt with almost 1200 degree air for hours on end could get a bit melty, and should be avoided.
Category: Air Force, Air National Guard
If it was a navy tanker, you can bet there would be a “loss of confidence “ and the nearest skipper would be out of a job! (It’s not just a job, it’s an adventure.)
Join the Navy and see the world,,,through a porthole
I remember in the early to mid 80s being “banned” from the old Myrtle Beach AFB, when not based on engine test runs but actual heavy weight take off we had a bird cause damage to the surface of the aerodrome.
Due to Soviet Bear activity along the east coast we had RON’d at MB as they had rooms for the crew (E-3 AWACS) on base When we launched the next day to meet the Bears we did a static max gross weight takeoff.
A friend joined the Navy 1954-1958 and was a scope dope on board a converted WW2 Liberty ship which was th USS Guardian YARG 1 Radar picket ship which went up and down the east coast waiting for the russian bombers to. This was called the Dew line and had Nike Bases up and down the coast waiting but no bombers so the missles were taken out and that was that.
We used to sit at a red light and get the rears lit up while
stepping on the brakes. The scars left on the pavement
lasted for years.