v2.vidman.ca/video/runway_crash.html

On May 10, 2005, at 1930 central daylight time, a McDonnell Douglas DC-9-51, N763NC, collided with an Airbus A-319-114, N368NB, during taxi resulting in substantial damage to both airplanes near gate G10, at Minneapolis/St. Paul International Airport (MSP), Minneapolis, Minnesota. Both airplanes were operated by Northwest Airlines Inc. (NWA) under Title 14 Code of Federal Regulations (CFR) Part 121 as scheduled-domestic passenger flights 1495 (N763NC) and 1849 (N368NB). Visual meteorological conditions prevailed at the time the accident. Both airplanes were evacuated after the collision. N763NC's captain received serious injuries, the first officer received minor injuries, and a flight attendant received minor injuries. One flight attendant aboard N368NB received minor injuries. One ramp service agent received minor injuries. N763NC departed Port Columbus International Airport (CMH), Columbus, Ohio, at 1826 eastern daylight time and with a scheduled destination to MSP.

N763NC experienced a reported loss of right hydraulic system fluid quantity during a climb to cruise from CMH. The flight continued to MSP where a landing was made without incident. The flight then taxied under its own power to gate G10 where it stopped and awaited a tow into the gate while N368NB was being pushed back by a tug. N763NC then moved forward and impacted the right wing of N368NB. Both airplanes were evacuated using N763NC's rear airstair door and N368NB's front left slide.

Examination of N763NC's right hydraulic system revealed the right hydraulic reservoir fluid quantity was below "EMPTY," and the left hydraulic reservoir fluid quantity was above "FULL." The right side hydraulic system was pressurized with hydraulic fluid and a leak from the rudder shutoff valve housing was noted. The rudder shutoff valve, part number 3772374-5503 G, serial number RON 1185, had a recorded total time in service of 62,436 hours. The rudder shutoff valve was removed and sent to the National Transportation Safety Board's Materials Laboratory for further examination.

Parties to the investigation are the Air Line Pilot Association, Aircraft Mechanics Fraternal Association, Federal Aviation Administration, Northwest Airlines Inc., and the Professional Flight Attendants Association.

Only 7.12 years in service.

He ... he ... he ... stuffed it in the APU and posted ... video!!!

Too much info missing here --


So, did that part fail and cause loss of control during the taxi?  

Did that part somehow cause one reservoir to be over-full and the other to be below empty?

When was the part supposed to be replaced?

Was there mechanic error?  Pilot error?  What caused the crash?

Quoted: Only 7.12 years in service.

Ah... no!

For that to be true the part had to be in full operation 24/7 365 for 7.12 years.  I am pretty sure hours are calculated by counting operational hours, not how long the item had been installed on the airframe.

I am thinking there might have been a considerable number of hours of down time during the time it took for that part to have that many hours of operation.  Maybe 20 years give or take.

One hydraulic system always has a higher pressure than the other. A leak between systems, due to something like bad o-rings on a spool valve, will mean the higher pressure system will deplete while the lower pressure system will overfill. But with redundant hydro power for brakes and nosewheel steering, it still doesn't explain the crash.