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#1
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Tow Hook on Cessna 180 - Update
Thanks for all the private responses. I don't have everything needed
for a legal installation yet but I am now relatively certain it is possible. Neal Pfeiffer was kind enough to put me in touch with Charles Pate at Cessna's Structural Engineering Department. Charles directed me to the FAA's Advisory Circular 43.13-2A figure 8.9 which is online at: http://www.airweb.faa.gov/Regulatory...visoryCircular ..nsf/1ab39b4ed563b08985256a35006d56af/e533bb05389c90e486256a54006e47b2/$FILE /Chapter%201-8.pdf If it wraps cut and paste it as required to make a link. It gives general guidelines for installing tow hooks on tailwheel and tricyle gear airplanes. He also forwarded a document file which described Cessna's testing of 100 series aircraft for towing and how nearly all structurally handle 1,200 lbs x 150% at various tow angles. This document is probably available on letterhead from Cessna's Structural Department. Allow at least a couple of weeks if you need a copy. Mr. Pate also sent photos of an installation he saw in Texas. The best information he sent were some unofficial copies of the Javelin Aircraft STC for the tow-hook installation. He said that David Blanton Sr. who passed away a few years ago donated the tow-hook STC to the SSA. The STC drawing shows how to fabricate a steel bracket that connects to the tailwheel using longer versions of the original through-bolts. It is a very clean installation. I have been told Gasser Banner can supply the bracket and the Schweizer hook. I have contacted the SSA about purchasing the STC and Gasser Banner about getting the Bracket and Hook. Interesting that the Javelin STC uses a nylon cord running from the hook along the outside of the fuselage through the pilot side window tied to the "assist strap" with a specified amount of slack. To release the tow line you pull on the cord. Seems like a very elegant solution - especially if you only plan on towing ocassionally. I hope the SSA has its act together enough to market the STC. Hope this will be helpful to someone else in the future. |
#2
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"Stuart Grant" wrote in message om... Charles Pate at Cessna's Structural Engineering Department. Charles directed me to the FAA's Advisory Circular 43.13-2A figure 8.9 which is online at: http://www.airweb.faa.gov/Regulatory...visoryCircular ..nsf/1ab39b4ed563b08985256a35006d56af/e533bb05389c90e486256a54006e47b2/$FILE /Chapter%201-8.pdf Try this one: http://tinyurl.com/qe6d Vaughn |
#3
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Please reconsider:
a. Any use of the Schweizer release for a tow hook. It doesn't work under high side loads. It is outdated and should be discarded. Use a Tost release. b. Any use of a rope along the fuselage for release actuation. Too much stretch plus doesn't give you any force multiplication when things go wrong and you need to ensure the ability of the tow pilot to release. AC 43.13 Part 2A figure 8.3 shows a 5:1 lever. This is what you need to get leverage and ensure that the tow pilot can release. But then also with a lever there are issues with ensuring pilot access to the lever in emergency. So a lot of thought as to the lever design and location is required. AC43.13 Part 2A para 132c talks about 1/16" steel cable minimum. Again over a long length this is too stretchy. Use 1/8" aircraft cable. Try for best modern practice, not just using old data because it is available. A search of r.a.s archives will probably turn up more useful commentary. Roger Druce "Stuart Grant" wrote in message om... Thanks for all the private responses. I don't have everything needed for a legal installation yet but I am now relatively certain it is possible. Neal Pfeiffer was kind enough to put me in touch with Charles Pate at Cessna's Structural Engineering Department. Charles directed me to the FAA's Advisory Circular 43.13-2A figure 8.9 which is online at: http://www.airweb.faa.gov/Regulatory...visoryCircular ..nsf/1ab39b4ed563b08985256a35006d56af/e533bb05389c90e486256a54006e47b2/$FILE /Chapter%201-8.pdf If it wraps cut and paste it as required to make a link. It gives general guidelines for installing tow hooks on tailwheel and tricyle gear airplanes. He also forwarded a document file which described Cessna's testing of 100 series aircraft for towing and how nearly all structurally handle 1,200 lbs x 150% at various tow angles. This document is probably available on letterhead from Cessna's Structural Department. Allow at least a couple of weeks if you need a copy. Mr. Pate also sent photos of an installation he saw in Texas. The best information he sent were some unofficial copies of the Javelin Aircraft STC for the tow-hook installation. He said that David Blanton Sr. who passed away a few years ago donated the tow-hook STC to the SSA. The STC drawing shows how to fabricate a steel bracket that connects to the tailwheel using longer versions of the original through-bolts. It is a very clean installation. I have been told Gasser Banner can supply the bracket and the Schweizer hook. I have contacted the SSA about purchasing the STC and Gasser Banner about getting the Bracket and Hook. Interesting that the Javelin STC uses a nylon cord running from the hook along the outside of the fuselage through the pilot side window tied to the "assist strap" with a specified amount of slack. To release the tow line you pull on the cord. Seems like a very elegant solution - especially if you only plan on towing ocassionally. I hope the SSA has its act together enough to market the STC. Hope this will be helpful to someone else in the future. |
#4
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Phil. Glider Council put Tost hooks on both our Pawnee and L-19. I
believe our tow pilots would highly endorse the set up for safety considerations. contact me if you want to talk to someone about the approval process. Chip Fitzpatrick |
#5
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Stuart
Before useing a Schweizer tow rig give serious consideration to the info on this website http://home.att.net/~jdburch/index.htm I too would reccommend a tost tow rig only. Far safer for both the tow pilot and glider. NTSB stats show on average one tow pilot death each year- upsets on tow with no chance of recovery. I think the FAA data is way out of date and should have been revisited long ago. Good luck Rod |
#6
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See also the article on upset accidents, causes and avoidance at
http://www.glidingmagazine.com/ListF...Dtl.asp?id=327 , by Chris Rollings. Note also that the BGA has a modification to the Schweizer hook, approved by the U.K. C.A.A., to incorporate a roller bearing in the hook to make release under heavy load much easier. W.J. (Bill) Dean (U.K.). Remove "ic" to reply. "Rod Pool" wrote in message m... Stuart Before using a Schweizer tow rig give serious consideration to the info on this website http://home.att.net/~jdburch/index.htm I too would recommend a tost tow rig only. Far safer for both the tow pilot and glider. NTSB stats show on average one tow pilot death each year- upsets on tow with no chance of recovery. I think the FAA data is way out of date and should have been revisited long ago. Good luck Rod |
#7
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W.J. (Bill) Dean (U.K.). wrote: See also the article on upset accidents, causes and avoidance at http://www.glidingmagazine.com/ListF...Dtl.asp?id=327 , by Chris Rollings. Note also that the BGA has a modification to the Schweizer hook, approved by the U.K. C.A.A., to incorporate a roller bearing in the hook to make release under heavy load much easier. W.J. (Bill) Dean (U.K.). Remove "ic" to reply. "Rod Pool" wrote in message . com... Stuart Before using a Schweizer tow rig give serious consideration to the info on this website http://home.att.net/~jdburch/index.htm I too would recommend a tost tow rig only. Far safer for both the tow pilot and glider. NTSB stats show on average one tow pilot death each year- upsets on tow with no chance of recovery. I think the FAA data is way out of date and should have been revisited long ago. Good luck Rod -- Peter D. Brown http://home.gci.net/~pdb/ http://groups.yahoo.com/group/akmtnsoaring/ |
#8
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The SSA was kind enough to mail me nice copies of STC's issued to Javelin
Aircraft Company for tow hook installation on Cessna 180, 185 & 321 Aircraft (STC SA271CE) and for Cessna 120, 140, 170 & 305 Aircraft (STC SA268CE). The STC's include many variants of the models listed. Both STC's reference Cessna Report No. S-000-134 (Page iii) Revision B dated 5/3/62 - which is probably the Cessna Engineering Analysis. Gasser Banner says they have not manufactured brackets and hooks for the Cessna 180 under their STC for many, many years but will sell the documents needed for fabrication for $75 - which is a modest cost considering the hassle. I may purchase just to see how it compares with the Javelin method. I have gotten lots of e-mail recommending using a TOST hook or inverted installation of the Schweizer hook. I have e-mailed TOST hoping to get information on their E85 release - mainly so I can figure out how to mount it on the 180 tailwheel (not a leaf spring) and rig a release. I am still assembling material for review by my A&P/IA so I don't buy anything I won't actually be able to get approved. None of the experts liked the idea of pulling the rope for release and pointed out that the FAA Advisory Circular recommends a lever with a 5:1 mechanical advantage. Rod's link below shows 337-approved inverted installation of Schweizer hook on a Pawnee leaf spring tailwheel. Thanks for all the comments. I will post what I find out from TOST. Stuart Rod Pool wrote: Stuart Before useing a Schweizer tow rig give serious consideration to the info on this website http://home.att.net/~jdburch/index.htm I too would reccommend a tost tow rig only. Far safer for both the tow pilot and glider. NTSB stats show on average one tow pilot death each year- upsets on tow with no chance of recovery. I think the FAA data is way out of date and should have been revisited long ago. Good luck Rod |
#9
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Tow Hook on Cessna 180 - Update
Hello Stuart,
Thank you for all the information. I am planning to install tow hook on our C180 in India. I badly need STC for installing hook otherwise local regulatory authority will not spar me. Please advise,How can get SSA copies of STC's issued to Javelin Aircraft Company for tow hook installation on Cessna 180. regards Ahmed |
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