rage1018 Posted October 13, 2011 Share Posted October 13, 2011 Good day to all. I frequent this website but I think this is the first time that I'm posting here to ask a technical question. I just like to be enlightened regarding what happend to us just last week. aircraft was a c-130H model. We were on a rolling take off when we noticed that the #3 TIT got stucked in 900 while all the other 3 engines were at 1010. We decided to abort the take off and I remember that the airspeed was around 80 kts that time. My PIC immediately put the power levers to FI and used the brakes to stop the aircraft. He did not use the outboard engines for reverse. when we finally completed the abort and while taxiing back to our ramp we noticed that the aircraft was bouncing a little. we immediately inspected the aircraft after shutdown and we found out that the lefthand forward main landing gear had serious shredding to the point that i can see the plies. the tire had shredding on only one side and you can tell by looking at it that the tire got stuck for quite a significant time compared to the other 3. luckily the tire did not burst. The first thing that came to my mind was that the anti skid did not work on this landing gear. we did check the anti skid prior to take off. transducers were checked and was found to be OK. what do you think can cause this? Thanks in advance. rage from Philippines Quote Link to comment Share on other sites More sharing options...
Ben Legere Posted October 13, 2011 Share Posted October 13, 2011 If you came to a complete stop on an aborted takeoff with just the brakes a flat spot on a tire would be nothing to worry about if the anti skid system checked good during an antiskid ops check. If you did not come to a complete stop and didn't drop below 15 knots while applying the brakes hard then there would be reason to dig into this further. Under 15 knots the antiskid system is not required to operate. Once the transducers slow down enough to where they can not send out a sufficient signal to your antiskid control box the antiskid will become inop preventing and false signals from disrupting brake operation during low speed taxying. When the antiskid system loses sufficient signal you can easily lock up a brake and leave a flat spot on a tire. With a locked up wheel it only takes a couple of seconds to blow a tire. I have seen aircraft that have only drug a tire about 30ft that have completely blown the tire. Even at 15kts a locked up wheel will drag 22ft in one second which is enough to significantly wear a tire down to the point where it will be in the chord. Quote Link to comment Share on other sites More sharing options...
rage1018 Posted October 13, 2011 Author Share Posted October 13, 2011 thanks ben we did come to a full stop on that aborted take-off. is it possible that if you are taxiing under 15kts and brake hard that only one tire will have a flat spot? since anti skid is no longer operative under 15kts then should't all main landing gears should show signs of shredding/flat spot after breaking hard for a couple of seconds or more or is it possible for some transducers to be less sensitive than the other transducers for the anti skid to be inoperative at 15kts or below? sorry for asking too much hehe. still new in flying c-130s. :) Quote Link to comment Share on other sites More sharing options...
Dan Wilson Posted October 23, 2011 Share Posted October 23, 2011 (edited) There will always be differences between the braking action on the four tires, depending on brake condition, brake temps, if the pilot had more pressure on the left pedal than on the right and several other variables. Almost everything has a tolerance range which will allow things to operate just a bit differently than the others; as you know, during an aborted takeoff the whole crew is pretty busy and that little pull to the left, that resulted in damage to the tire, could easily go unnoticed. That is why the pilot should have used his symmetrical good engines to assist in stopping instead of just braking action alone, its very easy to underestimate the amount of energy that gets transferred to the brakes in an emergency stop. When I first started flying back in 85 we had this silly ass four page chart in the performance manual you had to run for brake temps, I would like to say the kinetic energy was always in the hundreds of thousand or millions of pounds transferred to the brakes (thank god they got rid of that chart pretty damn quickly); so it doesn't take a whole bunch to thrash out a tire. Edited October 23, 2011 by Dan Wilson Kant spel Quote Link to comment Share on other sites More sharing options...
rage1018 Posted October 24, 2011 Author Share Posted October 24, 2011 thanks very much for the reply. now its clear to me. :) Quote Link to comment Share on other sites More sharing options...
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