Original Posted By: claude
Subject: Pietenpol-List: Re: Light weight Piet>>>I think that the outside cover plane on the>propeller should be keyed to the propeller shaft>to remove any twisting of the propeller bolts." .>>what he is describing is either a rough running>engine that backfires, one strong enough to shear>the bolts during acceleration or one that had a>ground strike. Otherwise there would be no>"twisting" of the bolts. Unless, of course, he is>over-revving it during a hand crank.>>________________________________________________________________________________
Pietenpol-List: Light weight Piet
Pietenpol-List: Light weight Piet
Original Posted By: Copinfo
Seems a recent article in BPANews had an article about a Chev 4 cyl Piecalled "PoplarPiet". It weighed 605 lbs. Looked very Ford like. Whileviewing stormbirds.com, about the ME-262's sa features in SPORT AV. thismonth,you can read about their pres. who had a fatal accident in a F-86.Click on to "fatal accident" and it will take you to a month by monthNTSB accident list. Just before Oshkosh there was an A Piet that losthis prop. Interesting reading for Ford builders.Leon S.________________________________________________________________________________
Seems a recent article in BPANews had an article about a Chev 4 cyl Piecalled "PoplarPiet". It weighed 605 lbs. Looked very Ford like. Whileviewing stormbirds.com, about the ME-262's sa features in SPORT AV. thismonth,you can read about their pres. who had a fatal accident in a F-86.Click on to "fatal accident" and it will take you to a month by monthNTSB accident list. Just before Oshkosh there was an A Piet that losthis prop. Interesting reading for Ford builders.Leon S.________________________________________________________________________________
Pietenpol-List: Re: Light weight Piet
Original Posted By: Doug
Below is the Piet "Lost prop" NTSB narrative mentioned by Leon. Note that the pilot blames the BHP design. Sad commentary on today when people are unable to admit fault and resort to blaming others when they are actually the boobs at blame!So ... how many of you swinging wooden props check the prop bolting seasonally?DG NTSB Identification: NYC99LA184. The docket is stored in the (offline) NTSB Imaging System.Accident occurred JUL-26-99 at COLLINS, OHAircraft: Troy PIETENPOL, registration: N6286A Injuries: 2 Uninjured. On July 26, 1999, about 0830 Eastern Daylight Time, a homebuilt Pietenpol, N6286A, was substantially damaged during a forced landing at Collins, Ohio. The certificated private pilot and passenger were not injured. Visual meteorological conditions prevailed for the flight that originated from a private grass airstrip at Valley City, Ohio; destined for Wood County Airport, Bowling Green, Ohio. No flight plan was filed for the personal flight conducted under 14 CFR Part 91. NYC99LA184On July 26, 1999, about 0830 Eastern Daylight Time, a homebuilt Pietenpol, N6286A, was substantially damaged during a forced landing at Collins, Ohio. The certificated private pilot and passenger were not injured. Visual meteorological conditions prevailed for the flight that originated from a private grass airstrip at Valley City, Ohio; destined for Wood County Airport, Bowling Green, Ohio. No flight plan was filed for the personal flight conducted under 14 CFR Part 91. During a telephone interview, the pilot stated that he was in cruise flight approximately 2,000 feet mean sea level. The engine lost all power, and he made a forced landing to a soybean field. During the landing, the left main landing gear folded under the airplane, and the right wing spar fractured. He added that examination of the wreckage revealed four bolts, which secured the propeller, were sheared. The respective four nuts and propeller were not recovered. The pilot believed that fatigue caused one bolt to shear, and a subsequent vibration occurred. The vibration caused the remaining bolts to shear. On this particular airplane, the propeller acted as a flywheel. The pilot stated that the absence of a flywheel would cause the engine to stop. When asked why he believed the bolts failed, the pilot stated: "After studying the prop hub on this plane, it is clear that this hub, that was designed in 1929, is not strong enough. I think that the outside cover plane on the propeller should be keyed to the propeller shaft to remove any twisting of the propeller bolts." The pilot last secured the propeller to the airplane approximately 1 year before the accident. Since then, he estimated that the airplane flew approximately 40 hours. According to the Safety Board's database, from January 1, 1989, through August 12, 1999, there was one other documented case of a propeller bolt failure on a Pietenpol (CHI92DEX04). However, the pilot stated that he knew of another Pietenpol owner that had a similar occurrence. ________________________________________________________________________________
Below is the Piet "Lost prop" NTSB narrative mentioned by Leon. Note that the pilot blames the BHP design. Sad commentary on today when people are unable to admit fault and resort to blaming others when they are actually the boobs at blame!So ... how many of you swinging wooden props check the prop bolting seasonally?DG NTSB Identification: NYC99LA184. The docket is stored in the (offline) NTSB Imaging System.Accident occurred JUL-26-99 at COLLINS, OHAircraft: Troy PIETENPOL, registration: N6286A Injuries: 2 Uninjured. On July 26, 1999, about 0830 Eastern Daylight Time, a homebuilt Pietenpol, N6286A, was substantially damaged during a forced landing at Collins, Ohio. The certificated private pilot and passenger were not injured. Visual meteorological conditions prevailed for the flight that originated from a private grass airstrip at Valley City, Ohio; destined for Wood County Airport, Bowling Green, Ohio. No flight plan was filed for the personal flight conducted under 14 CFR Part 91. NYC99LA184On July 26, 1999, about 0830 Eastern Daylight Time, a homebuilt Pietenpol, N6286A, was substantially damaged during a forced landing at Collins, Ohio. The certificated private pilot and passenger were not injured. Visual meteorological conditions prevailed for the flight that originated from a private grass airstrip at Valley City, Ohio; destined for Wood County Airport, Bowling Green, Ohio. No flight plan was filed for the personal flight conducted under 14 CFR Part 91. During a telephone interview, the pilot stated that he was in cruise flight approximately 2,000 feet mean sea level. The engine lost all power, and he made a forced landing to a soybean field. During the landing, the left main landing gear folded under the airplane, and the right wing spar fractured. He added that examination of the wreckage revealed four bolts, which secured the propeller, were sheared. The respective four nuts and propeller were not recovered. The pilot believed that fatigue caused one bolt to shear, and a subsequent vibration occurred. The vibration caused the remaining bolts to shear. On this particular airplane, the propeller acted as a flywheel. The pilot stated that the absence of a flywheel would cause the engine to stop. When asked why he believed the bolts failed, the pilot stated: "After studying the prop hub on this plane, it is clear that this hub, that was designed in 1929, is not strong enough. I think that the outside cover plane on the propeller should be keyed to the propeller shaft to remove any twisting of the propeller bolts." The pilot last secured the propeller to the airplane approximately 1 year before the accident. Since then, he estimated that the airplane flew approximately 40 hours. According to the Safety Board's database, from January 1, 1989, through August 12, 1999, there was one other documented case of a propeller bolt failure on a Pietenpol (CHI92DEX04). However, the pilot stated that he knew of another Pietenpol owner that had a similar occurrence. ________________________________________________________________________________
Pietenpol-List: Re: Light weight Piet
Original Posted By: Gordon Brimhall
>>I think that the outside cover plane on thepropeller should be keyed to the propeller shaftto remove any twisting of the propeller bolts." .what he is describing is either a rough runningengine that backfires, one strong enough to shearthe bolts during acceleration or one that had aground strike. Otherwise there would be no"twisting" of the bolts. Unless, of course, he isover-revving it during a hand crank.________________________________________________________________________________
>>I think that the outside cover plane on thepropeller should be keyed to the propeller shaftto remove any twisting of the propeller bolts." .what he is describing is either a rough runningengine that backfires, one strong enough to shearthe bolts during acceleration or one that had aground strike. Otherwise there would be no"twisting" of the bolts. Unless, of course, he isover-revving it during a hand crank.________________________________________________________________________________
Pietenpol-List: Re: Light weight Piet
Original Posted By: Bill Talbert
I have this type hub on my Scout.......the twisting or tork would beabsorbed by the two dowel pins that are in the crank and project into therear of der hub, no? I wonder what hub he did have? I do know these boltswere COMMERCIAL GRADE 5 or 8 bolts which are a BIG no-no to use aspropbolts. Also understand the second plane flying with this Piet was avirtual twin of this one....HIS 4 GR8 COMMERCIAL BOLTS WERE ABOUT TO FAIL ASWELL>>! There are more cookies in the jar....we just haven't smelled themyet...............Earl Myers-----Original Message-----
I have this type hub on my Scout.......the twisting or tork would beabsorbed by the two dowel pins that are in the crank and project into therear of der hub, no? I wonder what hub he did have? I do know these boltswere COMMERCIAL GRADE 5 or 8 bolts which are a BIG no-no to use aspropbolts. Also understand the second plane flying with this Piet was avirtual twin of this one....HIS 4 GR8 COMMERCIAL BOLTS WERE ABOUT TO FAIL ASWELL>>! There are more cookies in the jar....we just haven't smelled themyet...............Earl Myers-----Original Message-----
Pietenpol-List: Re: Light weight Piet
Original Posted By: walter evans
Subject: Pietenpol-List: Re: Light weight Piet>>>>I think that the outside cover plane on the>>propeller should be keyed to the propeller shaft>>to remove any twisting of the propeller bolts." .>>>>what he is describing is either a rough running>>engine that backfires, one strong enough to shear>>the bolts during acceleration or one that had a>>ground strike. Otherwise there would be no>>"twisting" of the bolts. Unless, of course, he is>>over-revving it during a hand crank.>>>Remember to check (and retorque) the prop bolts twice a year, we do thatand>that takes care of any posibility of bolt shear in wooden propellers.>>I know that the prop is barnished very well, but maybe humidity changes can>loose the bolt torque when in dry season...>>Saludos>>Gary Gower.>>________________________________________________________________________________
Subject: Pietenpol-List: Re: Light weight Piet>>>>I think that the outside cover plane on the>>propeller should be keyed to the propeller shaft>>to remove any twisting of the propeller bolts." .>>>>what he is describing is either a rough running>>engine that backfires, one strong enough to shear>>the bolts during acceleration or one that had a>>ground strike. Otherwise there would be no>>"twisting" of the bolts. Unless, of course, he is>>over-revving it during a hand crank.>>>Remember to check (and retorque) the prop bolts twice a year, we do thatand>that takes care of any posibility of bolt shear in wooden propellers.>>I know that the prop is barnished very well, but maybe humidity changes can>loose the bolt torque when in dry season...>>Saludos>>Gary Gower.>>________________________________________________________________________________
Pietenpol-List: Re: Light weight Piet
Original Posted By: "Shutic, Jeff"
>>>I think that the outside cover plane on the>propeller should be keyed to the propeller shaft>to remove any twisting of the propeller bolts." .>>what he is describing is either a rough running>engine that backfires, one strong enough to shear>the bolts during acceleration or one that had a>ground strike. Otherwise there would be no>"twisting" of the bolts. Unless, of course, he is>over-revving it during a hand crank.>Remember to check (and retorque) the prop bolts twice a year, we do that andthat takes care of any posibility of bolt shear in wooden propellers.I know that the prop is barnished very well, but maybe humidity changes canloose the bolt torque when in dry season...SaludosGary Gower.________________________________________________________________________________
>>>I think that the outside cover plane on the>propeller should be keyed to the propeller shaft>to remove any twisting of the propeller bolts." .>>what he is describing is either a rough running>engine that backfires, one strong enough to shear>the bolts during acceleration or one that had a>ground strike. Otherwise there would be no>"twisting" of the bolts. Unless, of course, he is>over-revving it during a hand crank.>Remember to check (and retorque) the prop bolts twice a year, we do that andthat takes care of any posibility of bolt shear in wooden propellers.I know that the prop is barnished very well, but maybe humidity changes canloose the bolt torque when in dry season...SaludosGary Gower.________________________________________________________________________________
> Re: Light weight Piet
Original Posted By: LaurenMWilliams(at)webtv.net (Lauren Williams)
Subject: Pietenpol-List: Re: Light weight Piet>PIET LIST; ALERT !!!!!!!!!!!!!!!!!!!!!!!!!> I have been in contact with the gentlemEn that have the two Ford powered>Piets from New York State, almost identical, one of which had thrown a prop>on the way to Broadhead '99 near Cleveland, Ohio. The fella that threw the>prop may be on this list too....(Mike Troy)> Anyways, I am bringing this up because that fella had "volunteered" to>submit a report to the N.T.S.B. as to what happened with his prop incident.>I got involved because I was in the aircraft fastener business for 15 years>to include manufacturing them. I also got involved because I wanted to know>what happened here as this was a "totally plans built" Piet (x2) right down>to the Model T prop hub......> This fella has indicated as noted below >>>>>that changes need to bemade>to the Piet prop hub as it is ..."a bad design" ...and prone to>failure....The 4 bolt plans hub is no good and we should ALL use the 6 bolt>Continental units that are out there. The 4 bolt unit has it's bolt circle>to close to the crank centerline, so on and so forth. OPINION not based on anything scientific. The down side of this is that the>N.T.S.B., because of this fella's allegations may recommend that ANYONE>ASKING THE FAA/MIDOs FOR AN EXPERIMENTAL HOMEBUILT certificate POWERED BY>A FORD MODEL A ENGINE...CANNOT USE THE PLANS BUILT 4 BOLT>HUB!!!!!!!!!!!!!!!!!!!!!!!!!!!!!> A couple more facts here...This fella stated that >>>>>>the hub wasbuilt>EXACTLY to the plans EXCEPT for the addition of a spacer disc of mild steel>of .090" thickness added between the hub and the backside of that prop. My>intent was to have that spacer a bigger diameter to match the diameter of>the prop boss say 5" instead of the 3.5" of the hub, in other words, spread>out the bearing area over the wood >>>>He torked>the quantity FOUR, GRADE 5 commercial bolts down by the "hearing thewood>start to crush method instead of using a tork wrench as I didn't have the>tork values anyway">>>>.3 of the 4 bolts severed just below the>shoulder of the bolt about 2 threads down OR there was 2 threads showing>above the nut, either way, the bolts let go right at the vicinity where the>shank meets the threads which is ALWAYS the weakest tork point......I>didn't use Grade 8 or 12 bolts as he didn't want them to work-harden any>farther.> The second Piet's owner removed his prop upon their return to N.Y.State.>This second owner found that his prop, the backside against the hub spacer,>was severly burned as in smelling of burned wood and had the appearence of>being burned ! That was that and there goes the above report.............>>>This NTSB recommendation comment did not come from that fella, it camefrom>THE FAA in a round about manner (from my friends that work for the FAA and>have their collective heads on straight) as something they (the Feds) would>or could adopt as an unwritten rule since they would have read the NTSB's>suggestion or something to this effect. I did not mention the Ford 4 bolt>issue, just "a mechanical issue with a vintage engine"........>> I don't want to trash this guy or us jump on his "case". I would>like you guys to anaylize this issue and pass this around to those of whom>you guys trust that can educatedly comment on the mechanics of what is>going on here. Have ANYONE who has a scientific opinion to contact me at>allaire(at)raex.com with any info that would be helpfull. I am doing this>because this incident happened in the CLEVELAND, Ohio MIDO / FSDO areawhere>I live. I have a 4 bolt hub SIMILAR to the plans unit. If this gets out of>hand, I will have to deal with it then ultimately the reast of you. This>way, I can collect GOOD data to combat this for all of us! Remember, with>the Feds, all it takes is ONE unsubstantiated comment to get their>monolithic ball rolling which is danged hard to stop!>> Anybody ever hear of ANYTHING happening like this before? Details?>> In my humble opinion, I don't think the guy had the prop bolts any way>near tight enough.........YES? NO?>Earl Myers, Ohio...humble and curious!>-----Original Message----->From: Gary Gower >To: Pietenpol Discussion >Date: Wednesday, September 29, 1999 5:14 PM>Subject: Re: Light weight Piet>>>>>>>I think that the outside cover plane on the>>>propeller should be keyed to the propeller shaft>>>to remove any twisting of the propeller bolts." .>>>>>>what he is describing is either a rough running>>>engine that backfires, one strong enough to shear>>>the bolts during acceleration or one that had a>>>ground strike. Otherwise there would be no>>>"twisting" of the bolts. Unless, of course, he is>>>over-revving it during a hand crank.>>>>>Remember to check (and retorque) the prop bolts twice a year, we do that>and>>that takes care of any posibility of bolt shear in wooden propellers.>>>>I know that the prop is barnished very well, but maybe humidity changescan>>loose the bolt torque when in dry season...>>>>Saludos>>>>Gary Gower.>>>>>>________________________________________________________________________________
Subject: Pietenpol-List: Re: Light weight Piet>PIET LIST; ALERT !!!!!!!!!!!!!!!!!!!!!!!!!> I have been in contact with the gentlemEn that have the two Ford powered>Piets from New York State, almost identical, one of which had thrown a prop>on the way to Broadhead '99 near Cleveland, Ohio. The fella that threw the>prop may be on this list too....(Mike Troy)> Anyways, I am bringing this up because that fella had "volunteered" to>submit a report to the N.T.S.B. as to what happened with his prop incident.>I got involved because I was in the aircraft fastener business for 15 years>to include manufacturing them. I also got involved because I wanted to know>what happened here as this was a "totally plans built" Piet (x2) right down>to the Model T prop hub......> This fella has indicated as noted below >>>>>that changes need to bemade>to the Piet prop hub as it is ..."a bad design" ...and prone to>failure....The 4 bolt plans hub is no good and we should ALL use the 6 bolt>Continental units that are out there. The 4 bolt unit has it's bolt circle>to close to the crank centerline, so on and so forth. OPINION not based on anything scientific. The down side of this is that the>N.T.S.B., because of this fella's allegations may recommend that ANYONE>ASKING THE FAA/MIDOs FOR AN EXPERIMENTAL HOMEBUILT certificate POWERED BY>A FORD MODEL A ENGINE...CANNOT USE THE PLANS BUILT 4 BOLT>HUB!!!!!!!!!!!!!!!!!!!!!!!!!!!!!> A couple more facts here...This fella stated that >>>>>>the hub wasbuilt>EXACTLY to the plans EXCEPT for the addition of a spacer disc of mild steel>of .090" thickness added between the hub and the backside of that prop. My>intent was to have that spacer a bigger diameter to match the diameter of>the prop boss say 5" instead of the 3.5" of the hub, in other words, spread>out the bearing area over the wood >>>>He torked>the quantity FOUR, GRADE 5 commercial bolts down by the "hearing thewood>start to crush method instead of using a tork wrench as I didn't have the>tork values anyway">>>>.3 of the 4 bolts severed just below the>shoulder of the bolt about 2 threads down OR there was 2 threads showing>above the nut, either way, the bolts let go right at the vicinity where the>shank meets the threads which is ALWAYS the weakest tork point......I>didn't use Grade 8 or 12 bolts as he didn't want them to work-harden any>farther.> The second Piet's owner removed his prop upon their return to N.Y.State.>This second owner found that his prop, the backside against the hub spacer,>was severly burned as in smelling of burned wood and had the appearence of>being burned ! That was that and there goes the above report.............>>>This NTSB recommendation comment did not come from that fella, it camefrom>THE FAA in a round about manner (from my friends that work for the FAA and>have their collective heads on straight) as something they (the Feds) would>or could adopt as an unwritten rule since they would have read the NTSB's>suggestion or something to this effect. I did not mention the Ford 4 bolt>issue, just "a mechanical issue with a vintage engine"........>> I don't want to trash this guy or us jump on his "case". I would>like you guys to anaylize this issue and pass this around to those of whom>you guys trust that can educatedly comment on the mechanics of what is>going on here. Have ANYONE who has a scientific opinion to contact me at>allaire(at)raex.com with any info that would be helpfull. I am doing this>because this incident happened in the CLEVELAND, Ohio MIDO / FSDO areawhere>I live. I have a 4 bolt hub SIMILAR to the plans unit. If this gets out of>hand, I will have to deal with it then ultimately the reast of you. This>way, I can collect GOOD data to combat this for all of us! Remember, with>the Feds, all it takes is ONE unsubstantiated comment to get their>monolithic ball rolling which is danged hard to stop!>> Anybody ever hear of ANYTHING happening like this before? Details?>> In my humble opinion, I don't think the guy had the prop bolts any way>near tight enough.........YES? NO?>Earl Myers, Ohio...humble and curious!>-----Original Message----->From: Gary Gower >To: Pietenpol Discussion >Date: Wednesday, September 29, 1999 5:14 PM>Subject: Re: Light weight Piet>>>>>>>I think that the outside cover plane on the>>>propeller should be keyed to the propeller shaft>>>to remove any twisting of the propeller bolts." .>>>>>>what he is describing is either a rough running>>>engine that backfires, one strong enough to shear>>>the bolts during acceleration or one that had a>>>ground strike. Otherwise there would be no>>>"twisting" of the bolts. Unless, of course, he is>>>over-revving it during a hand crank.>>>>>Remember to check (and retorque) the prop bolts twice a year, we do that>and>>that takes care of any posibility of bolt shear in wooden propellers.>>>>I know that the prop is barnished very well, but maybe humidity changescan>>loose the bolt torque when in dry season...>>>>Saludos>>>>Gary Gower.>>>>>>________________________________________________________________________________
Pietenpol-List: Re: Light weight Piet
Original Posted By: Gary Gower
PIET LIST; ALERT !!!!!!!!!!!!!!!!!!!!!!!!! I have been in contact with the gentlemEn that have the two Ford poweredPiets from New York State, almost identical, one of which had thrown a propon the way to Broadhead '99 near Cleveland, Ohio. The fella that threw theprop may be on this list too....(Mike Troy) Anyways, I am bringing this up because that fella had "volunteered" tosubmit a report to the N.T.S.B. as to what happened with his prop incident.I got involved because I was in the aircraft fastener business for 15 yearsto include manufacturing them. I also got involved because I wanted to knowwhat happened here as this was a "totally plans built" Piet (x2) right downto the Model T prop hub...... This fella has indicated as noted below >>>>>that changes need to be madeto the Piet prop hub as it is ..."a bad design" ...and prone tofailure....The 4 bolt plans hub is no good and we should ALL use the 6 boltContinental units that are out there. The 4 bolt unit has it's bolt circleto close to the crank centerline, so on and so forth. >>>>>the hub was builtEXACTLY to the plans EXCEPT for the addition of a spacer disc of mild steelof .090" thickness added between the hub and the backside of that prop. Myintent was to have that spacer a bigger diameter to match the diameter ofthe prop boss say 5" instead of the 3.5" of the hub, in other words, spreadout the bearing area over the wood >>>>He torkedthe quantity FOUR, GRADE 5 commercial bolts down by the "hearing the woodstart to crush method instead of using a tork wrench as I didn't have thetork values anyway">>>>.3 of the 4 bolts severed just below theshoulder of the bolt about 2 threads down OR there was 2 threads showingabove the nut, either way, the bolts let go right at the vicinity where theshank meets the threads which is ALWAYS the weakest tork point......Ididn't use Grade 8 or 12 bolts as he didn't want them to work-harden anyfarther.<<<<< The second Piet's owner removed his prop upon their return to N.Y. State.This second owner found that his prop, the backside against the hub spacer,was severly burned as in smelling of burned wood and had the appearence ofbeing burned ! That was that and there goes the above report.............This NTSB recommendation comment did not come from that fella, it came fromTHE FAA in a round about manner (from my friends that work for the FAA andhave their collective heads on straight) as something they (the Feds) wouldor could adopt as an unwritten rule since they would have read the NTSB'ssuggestion or something to this effect. I did not mention the Ford 4 boltissue, just "a mechanical issue with a vintage engine"........ I don't want to trash this guy or us jump on his "case". I wouldlike you guys to anaylize this issue and pass this around to those of whomyou guys trust that can educatedly comment on the mechanics of what isgoing on here. Have ANYONE who has a scientific opinion to contact me atallaire(at)raex.com with any info that would be helpfull. I am doing thisbecause this incident happened in the CLEVELAND, Ohio MIDO / FSDO area whereI live. I have a 4 bolt hub SIMILAR to the plans unit. If this gets out ofhand, I will have to deal with it then ultimately the reast of you. Thisway, I can collect GOOD data to combat this for all of us! Remember, withthe Feds, all it takes is ONE unsubstantiated comment to get theirmonolithic ball rolling which is danged hard to stop! Anybody ever hear of ANYTHING happening like this before? Details? In my humble opinion, I don't think the guy had the prop bolts any waynear tight enough.........YES? NO?Earl Myers, Ohio...humble and curious!-----Original Message-----
PIET LIST; ALERT !!!!!!!!!!!!!!!!!!!!!!!!! I have been in contact with the gentlemEn that have the two Ford poweredPiets from New York State, almost identical, one of which had thrown a propon the way to Broadhead '99 near Cleveland, Ohio. The fella that threw theprop may be on this list too....(Mike Troy) Anyways, I am bringing this up because that fella had "volunteered" tosubmit a report to the N.T.S.B. as to what happened with his prop incident.I got involved because I was in the aircraft fastener business for 15 yearsto include manufacturing them. I also got involved because I wanted to knowwhat happened here as this was a "totally plans built" Piet (x2) right downto the Model T prop hub...... This fella has indicated as noted below >>>>>that changes need to be madeto the Piet prop hub as it is ..."a bad design" ...and prone tofailure....The 4 bolt plans hub is no good and we should ALL use the 6 boltContinental units that are out there. The 4 bolt unit has it's bolt circleto close to the crank centerline, so on and so forth. >>>>>the hub was builtEXACTLY to the plans EXCEPT for the addition of a spacer disc of mild steelof .090" thickness added between the hub and the backside of that prop. Myintent was to have that spacer a bigger diameter to match the diameter ofthe prop boss say 5" instead of the 3.5" of the hub, in other words, spreadout the bearing area over the wood >>>>He torkedthe quantity FOUR, GRADE 5 commercial bolts down by the "hearing the woodstart to crush method instead of using a tork wrench as I didn't have thetork values anyway">>>>.3 of the 4 bolts severed just below theshoulder of the bolt about 2 threads down OR there was 2 threads showingabove the nut, either way, the bolts let go right at the vicinity where theshank meets the threads which is ALWAYS the weakest tork point......Ididn't use Grade 8 or 12 bolts as he didn't want them to work-harden anyfarther.<<<<< The second Piet's owner removed his prop upon their return to N.Y. State.This second owner found that his prop, the backside against the hub spacer,was severly burned as in smelling of burned wood and had the appearence ofbeing burned ! That was that and there goes the above report.............This NTSB recommendation comment did not come from that fella, it came fromTHE FAA in a round about manner (from my friends that work for the FAA andhave their collective heads on straight) as something they (the Feds) wouldor could adopt as an unwritten rule since they would have read the NTSB'ssuggestion or something to this effect. I did not mention the Ford 4 boltissue, just "a mechanical issue with a vintage engine"........ I don't want to trash this guy or us jump on his "case". I wouldlike you guys to anaylize this issue and pass this around to those of whomyou guys trust that can educatedly comment on the mechanics of what isgoing on here. Have ANYONE who has a scientific opinion to contact me atallaire(at)raex.com with any info that would be helpfull. I am doing thisbecause this incident happened in the CLEVELAND, Ohio MIDO / FSDO area whereI live. I have a 4 bolt hub SIMILAR to the plans unit. If this gets out ofhand, I will have to deal with it then ultimately the reast of you. Thisway, I can collect GOOD data to combat this for all of us! Remember, withthe Feds, all it takes is ONE unsubstantiated comment to get theirmonolithic ball rolling which is danged hard to stop! Anybody ever hear of ANYTHING happening like this before? Details? In my humble opinion, I don't think the guy had the prop bolts any waynear tight enough.........YES? NO?Earl Myers, Ohio...humble and curious!-----Original Message-----
Pietenpol-List: Re: Light weight Piet
Original Posted By: Earl Myers
In ref to the message about the prop hub,if you put a piece of paper betweenthe rear of the prop and the drive plate it will keep the slipping fromhappening and will not burn the back of the prop.Bill-----Original Message-----
In ref to the message about the prop hub,if you put a piece of paper betweenthe rear of the prop and the drive plate it will keep the slipping fromhappening and will not burn the back of the prop.Bill-----Original Message-----