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Aw139 track and balance. Help!
Hello all.
2 weeks ago we started have vertical vibration on M/R on FPOG only about 0.4 IPS and sometimes 0.5Ips . There is no recommend adjustment show on HUMS report. But as soos as the pilot pull the collective up during the ground run all vibrations disapear and when he lower the collective the vibration back again. also when pilot move the cyclic left or right ,fwd or aft all vibration disapear and when he put the cyclic to center the vibration back. as i said on the top the vibration only on ground when the pilot select the flight mode only. (On idle mode no vibration). Also on hover,cruise ,fast cruise no any vibration. Another thing to mention. If the piolt hover the aircraft and then land all vibration disapear as well and will not come again all the day even if he shut down the engines and start again at same day no vibration will show but when we park the aircraft overnight and try to start it on the morning the vibration will come again and will not stop unless the pilot hover the aircraft and then land. More than 10 years working as engineer on aw139 but the first time i had this issue. Any advise what can cause this problem? |
Undercarriage oleos? Check pressure
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I suggest that you put this question to the manufacturer, I m pretty sure you have plenty of manufacturers backup in your location. Also welcome to this forum, we don’t get to hear from many in the Middle East. |
Originally Posted by Salusa
(Post 10537380)
Undercarriage oleos? Check pressure
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Indeed, check oleos, check tire pressure, check main rotor dampers. Do you park it outside overnight? Temperature differences have effect on the dampers as well. Usually a 10 minute ground run should bring everything to an operational condition. If this does not work, our engineers turn to the log cards and start comparing balancing mass and pitch rod settings with the current conditions. (Sometimes the trim tabs, however, considering your situation these can be ruled out - i.e. fast forward flight only). Please let us know if the situation has resolved and what action led to a possible solution. Good luck! |
Originally Posted by breakdip
(Post 10537397)
Indeed, check oleos, check tire pressure, check main rotor dampers. Do you park it outside overnight? Temperature differences have effect on the dampers as well. Usually a 10 minute ground run should bring everything to an operational condition. If this does not work, our engineers turn to the log cards and start comparing balancing mass and pitch rod settings with the current conditions. (Sometimes the trim tabs, however, considering your situation these can be ruled out - i.e. fast forward flight only). Please let us know if the situation has resolved and what action led to a possible solution. Good luck! The problem HUMS system read the vibration but not recommand any adjustments. Something strange! |
Originally Posted by nomorehelosforme
(Post 10537391)
I suggest that you put this question to the manufacturer, I m pretty sure you have plenty of manufacturers backup in your location. Also welcome to this forum, we don’t get to hear from many in the Middle East. But maybe somebody had this problem before and can give us some information. |
I've flown other types of aircraft that suffered vertical bounce problems caused by SAS/autopilot/gyro faults.
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Might be worth checking MRG/bx mounting,and swashplate....
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ENG, I believe that the problem are the elastomeric bearings. When they are cold, at first start in the morning, one may have a different rigidity and this could be the cause of the vibration because a blade goes out of track. When they became hot the rigidity is equal and the track is restored.
You may check the MR track at first start and then when the vibration has disappeared. |
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