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Old 15th Jul 2005, 11:01
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Centaurus
 
Join Date: Jun 2000
Location: Australia
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I flew for an airline in the Central and South Pacific region operating 737-200's There were three specific case of brakes welding on following mis-use. First one was at Manila, max weight take off on very long runway. The 80 knot check on take off showed a 20 knot discrepancy (due to, as it turned out, water in the pitot systen after heavy overnight rain).

The captain elected to continue the take off (he was in denial?) and asked the F/O for another airspeed call when the F/O IAS read 100 knots. In other words he delayed making a decision.

The F/O then called 100 knots and as the captain ASI was still in error, the captain decided to abort. He applied full braking and reverse and pulled up with 4000 ft to spare. He then taxied to the terminal, parked the brakes, blew the fusible plugs and welded the brakes on. Not very good airmanship.

Case 2. The chief pilot conducting training at an island runway 7000 ft long. This involved successive full stop landings, and as the wind was calm, after take off a dumb-bell turn was carried out to land on the opposite end of the departure runway. The gear was retracted after take off in each case. OAT 30 C. After 30 minutes of training meaning around six full stop landings, the aircraft was taxied to the terminal to await passengers. The brakes were parked and shortly after the fusible plugs let go. I don't know if the brakes welded on.

Case 3. Max structural take off on 11,000ft runway - wind calm good weather. "A" system failure after landing gear selected up. Captain held for 20 minutes to sort out problem and had no choice but to return for non-normal A system failure landing which requires manual dropping of the landing gear and flap 15 landing. Under these conditions the thrust reversers are operated by the standby hydraulkic system and are slow to operate due small capacity pump.

Captain lands nicely near max take off structural weight and goes for full reverse. As advertised in the FCTM somewhere, the thrust reversers are very slow to open and as it is years since the captain has done this exercise in the simulator, he thinks he has now got a double failure of the reverse thrust system because the aircraft is really speeding down the runway and bugger all decelleration. He stamps on the pedals and applies maximum braking by which time when the reverse does finally come good, he has already slowed down to a speed where reverse is now ineffective.
He stops the 737 on the runway with 4000 ft remaining, in the belief that with an loss of system A he has no nose-wheel steering. He then instinctively sets the park brake on while he talks to ATC. Soon after the fusible plugs do their job and the brakes then weld on. As the runway was 11,000 ft long, and being wise after the event, it could be argued that he stuffed up by not being aware of slow reverse operation with loss of system A and could have gone real easy on the brakes allowing the aircraft to use the full length.

Under high speed stop conditions where the brakes become very hot, one option is not to apply the park brakes which really clamps the brakes on 3000 psi, but simply after stopping, lightly apply gentle pressure to one brake pedal sufficient to prevent the aircraft from moving under idle thrust until chocks are inserted.

This may save one set of brakes if nothing else. I have seen this method used where brakes were hot after landing on very short wet runways. It works a treat as you can easily stop the aircraft from moving by holding just a teensy weensy amount of pedal on the wheel of your choice!
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