Pietenpol-List: BRS for Pietenpol/ regarding elevator control failure
Posted: Thu Feb 03, 2005 9:12 pm
Original Posted By: Rcaprd(at)aol.com
To D.J. Vegh:Do you know the location of the failure in the Pietenpol elevator control systemat Falcon Field? I"m sure we Pietenpol jockeys would like to know any details.When I built my Pietenpol in 1970, I foolishly used aluminum pulleys in the forwardelevator cable circuit. After 159 hours, I discovered the forward "up" elevatorcable had frayed and I replaced it. Then, after 278 hours, the forward"down" cable frayed. The failures were at the twin pulleys on the torque tubejust under the front of the rear seat. Probably dust combined with the aluminumpulleys caused excessive cable wear at this point.I then replaced both cables and substituted micarta pulleys for the aluminum ones.The airplane now has 741 hours on it and no further cable problems have surfaced.Needless to say, I keep a close watch on them. It is easy to check themby feeling the cable as it runs through your fingers when the stick is movedback and forth and this is a part of my pre-flight inspection. Should you snaga finger with a broken wire, it is much better than losing elevator controlin flight! (But if one uses a piece of cloth instead of one's pinky for this procedure,it will catch on a broken wire alerting you that there is a problem,and the finger will be spared.)My Pietenpol, like many of them, has no elevator trim for backup. And it has alwaystended to be a bit nose-heavy in the air, solo or dual. An elevator controlfailure is something I would rather not think about.Even with a BRS, one must build and fly carefully, and practise diligent maintenancebecause the BRS may not be able to save you in some circumstances. The wordsof Major Hereward deHavilland (brother of Sir Geoffrey) come to mind:"The only way for a flying man to keep alive [is] to be apprehensive." (Quotedfrom THE LONELY SEA AND THE SKY by Sir Francis Chichester, 1964.)Graham Hansen (Pietenpol CF-AUN)________________________________________________________________________________
To D.J. Vegh:Do you know the location of the failure in the Pietenpol elevator control systemat Falcon Field? I"m sure we Pietenpol jockeys would like to know any details.When I built my Pietenpol in 1970, I foolishly used aluminum pulleys in the forwardelevator cable circuit. After 159 hours, I discovered the forward "up" elevatorcable had frayed and I replaced it. Then, after 278 hours, the forward"down" cable frayed. The failures were at the twin pulleys on the torque tubejust under the front of the rear seat. Probably dust combined with the aluminumpulleys caused excessive cable wear at this point.I then replaced both cables and substituted micarta pulleys for the aluminum ones.The airplane now has 741 hours on it and no further cable problems have surfaced.Needless to say, I keep a close watch on them. It is easy to check themby feeling the cable as it runs through your fingers when the stick is movedback and forth and this is a part of my pre-flight inspection. Should you snaga finger with a broken wire, it is much better than losing elevator controlin flight! (But if one uses a piece of cloth instead of one's pinky for this procedure,it will catch on a broken wire alerting you that there is a problem,and the finger will be spared.)My Pietenpol, like many of them, has no elevator trim for backup. And it has alwaystended to be a bit nose-heavy in the air, solo or dual. An elevator controlfailure is something I would rather not think about.Even with a BRS, one must build and fly carefully, and practise diligent maintenancebecause the BRS may not be able to save you in some circumstances. The wordsof Major Hereward deHavilland (brother of Sir Geoffrey) come to mind:"The only way for a flying man to keep alive [is] to be apprehensive." (Quotedfrom THE LONELY SEA AND THE SKY by Sir Francis Chichester, 1964.)Graham Hansen (Pietenpol CF-AUN)________________________________________________________________________________