I just completed the installation of 3' extended gear on my 1956 PA-18A including the installation of new hydrosorbs and bungees. I use 8.50 x 6 wheels in the non-snow season and AeroSki M2000's in the winter. While researching the project, I was advised to install one 1280HD and one 1380HD bungee per side by a couple of different folks with experience in the matter. According to a number of suppliers, two 1280HD's are apparently standard on a PA-18 so the recommendation seemed reasonable. I placed my order but signals must have been crossed because I received two 1280's and two 1380's instead of the HD versions. We went ahead and installed those because the combination was virtually identical in test load to two 1280HD's (see data below). Once we had the gear together, we noticed right away that it was very stiff - when rocking a wingtip in the shop, only the tires flexed.
15.5 Bungee Cord Installation Notes: - Installing bungee cord is at least a two man job. Microsoft Word - 15 Bungee Landing Gear.doc Author: npark Created Date. New die spring landing gear on a Pietenpol. This type of gear is an improvement over bungees. The 2.25″ outer tube is fixed to landing gear frame at the top.
I was advised not to worry about it and that things would soften up over time. I put a few hours on the wheels and switched to skis a couple of weekends ago. All I can say is that takeoffs and landings are bone jarring when on any packed snow and all of the energy seems to go right up into the airframe. The actual gear is not absorbing anything and I'm worried about the gear attach fittings and longerons. I've done at least thirty take-offs and landings and this gear is not softening up. I had a look at the bungee manufacturer's web site and here is what I found for bungee size and test loads for the different bungees: 1080 5/8' x 8' 750 lbs 1080HD 5/8' x 8' 900 lbs 1280 3/4' x 8' 750 lbs 1280HD 3/4' x 8' 950 lbs 1380 13/16' x 8' 1160 lbs 1380HD 13/16' x 8' 1460 lbs According to this manufacturer, 1080HD's are standard for the PA-18. Two per side would equal an 1800 lb test load.
In my case, with a 1280 and a 1380, my test load is 1910 lbs. I'm surprised that this minor difference in test load would make such a large difference in actual feel on the plane. I need to make a change as this bungee combination is simply too harsh on my plane (while on skis anyway). Unfortunately, I don't know what the bungee spec was on the stock gear before we did this mod but the energy absorption was very reasonable (although the hydrosorbs were completely worn out).
According to various suppliers I talked to, it seems that a lot of PA-18 owners will tend to install the heavier bungees for longevity but they often have larger tires installed to - so they're not relying on the gear itself to absorb much shock. I need to set my bungees up for ski use. What do you guys recommend for a bungee combination? I really appreciate your comments and experiences. Regards; Chris.
Chris: For what it is worth. The 'smaller the tire the lighter the cords'. If I recall correctly the original 150 hp cubs with the 800 x 4 tires came with 1280 cords. These were OK when used in standard category and worked well to soften the 'crash and go' student landings. When we converted them to sprayers we would install the 1280HD cords; otherwise the gear would sag under load.
When you start putting the larger tundra tires on, then it starts to depend upon the tire size. For example: I used the old 25 x 11 x 4 tires with 1280HD cords and did fair. When installing the larger 30 or 31 inch tundra tires the gear would start to 'sag' or 'spread' especially when you did any sort of tight turn when parking, like with one brake set. It appears that the increased leverage of the 'longer arm' created by the tire was enough to spread the gear. The 1280HD cords could be fairly new and still do this. It was even worse in colder weather.
10 or 15 years ago it started to become common in Alaska to use one 1280HD cord with one 1380HD cord. This all but eliminated the sag on the ground but does stiffen the ride some.
Not a problem with the softer tires. If you are not going to run large tires and only skis then perhaps the 1280 or 1280HD would be better. Also you would want to look for cord part numbers with a CW suffix. 1280HDCW (for cold weather). They seem to just be better quality cords and last a lot longer.
Landing Gear I'm out of the loop for conduit installations. The following is for reference only, not intended to imply I still do the installations. If you want me to install your conduits or landing gear wiring harnesses please read this for the description of your work portion of the click installation, and/or this for the click installation, and; see also the 'Migrant Worker' link for any planned trips. Landing Gear Conduits. The conduits seem to be the hot topic so we'll cover it first. Likewise landing gear transmissions are a hot topic; they have their own link. Conduits - These are the main landing gear retraction system push - pull cables.
The nose gear uses a push - pull rod. The real way to check those conduits is just like the SM states. Disconnect both ends and check for freedom of movement. Because it’s a pain to do all the work to get there, at the very least disconnect the conduits and nose gear at the gear ends and check movement of both conduits using the manual lever. However it’s difficult without experience to know what too much or correct resistance feels like. And keep in mind, without the “load” of the gear on any conduit you will get a false indication. The “load” will exacerbate a problem in the curved area where the wear occurs; each conduit makes a 90-degree bend under the spar.
One good note, if you do the suggested method and find a problem, you haven’t wasted any time. Why - because the access time can be converted into conduits replacement time.
Count on a whole day to do it correctly, that means the entire landing gear adjustment procedure. Then one would ask the question, “Why not “invest” that time in an upgrade – new conduits”.
See the logic? Hopefully resistance to replacing these critical components will diminish. As one would guess I get a lot of inquiries about the conduits and their 'resistance' as measured using the torque adapters. Note - see the ICS tool loan program page. The reports are even passing the prescribed test, the 30 CB opens near the up-limit.
It's the conduits. I've not been informed ever of a torque test failing; tell me if you have - details? Note - Comanche Gear does not hold a PMA for these conduits; that belongs to.
Their P/N is W455-180; about $400 each cheap in my opinion - good guys Webco. The conduit supply from Webco is periodic; they have a standing order from their supplier. Since these are a popular item you had best plan ahead; they may not be available if you call them too late in a purchase cycle. I know that I blab a lot so bear with me on this. I'm pro-active concerning landing gear maintenance, so if you phone me be prepared to get an ear-full. An ear-full of reasons why you should just do it; when were these push-pull cables lubricated?
Another justification; replacing the conduits will offer the opportunity to examine the entire retraction system; if you find additional problems count it a blessing. Those potential problems newly discovered and properly remedied are an asset to the security of your retraction system; and the log book and maintenance records. This will instill confidence in you and a future purchaser. View from the wheel well; conduit & mounting bracket The above photos are found in the manual I've written as described below. I've performed 48 of these conduit installations until my rotator let go again 3-rd time and every hint learned is conveyed in this manual. FWIW I was an engineer at IBM and one of my responsibilities was writing engineering reports.
Piper Comanche Landing Gear Bungee
This for writing is partially derived from that experience; and as supported by positive feedback from purchasers of this manual. Click on the cover page above for a description of this manual and components included with the manual purchase.
Click here for of the above manual. Someone suggested that I change the name of this manual to, 'Landing Gear for Dummies'; not a bad idea. I am writing another manual covering the setup procedures and adjustment aspects involved in the 1000-hour AD 77-13-01. Click on the photo above for description of the FBO tooling and parts components available for purchase. Is this what you call 'Conduit Denial'? Click on the link above for a procedure Incorporating Maurice Taylor's file.
See also following below - landing gear bungee rollers. The bungee cords have a shelf life of 5 years out of direct sunlight and heat. The link below shows how to figure the date of manufacture by the color code Landing Gear Bungee Rollers While replacing the bungee cords be prepared to find seized bungee rollers; and after 54 years of misunderstood service I bet that many of them are seized. Click on the photo above for the proper installation of these rollers, and a repair description if you have frozen rollers. Note - this photo illustrates an improper installation of the roller on the bungee arm.
Main Landing Gear Assist Springs Click on the above photograph for information about this spring and its replacement procedure. The photo above illustrates two issues, a MLG spring that hasn't been replaced as required, and the bolt see finger is installed backwards. As you might expect I offer a couple “kits” to replace these springs. $55.00 Basic kit contents for replacing the MLG assist springs. And the $82.00 super-duper version, includes EXCHANGE-ONLY cadmium plated spring swivel assemblies.
The 1000-Hour AD. I have written an instruction manual to cover this task; 71 pages with more information than you probably want to know. Lots of color photos, assembly drawing inserts, pages of part numbers utilized right down to the cotter pins. $100 and I guarantee it will educate you and your mechanic/technician.
1000-hour You already have or can easily obtain a copy of this AD. The contents of are my recommendations for better understanding of the scope of this critical operation; there is more to it than you think. Referenced in this AD is SL-782 which is addressed below. TOOL LOAN for R&R of the mount bushings at the aft ends of the nose gear drag links. Includes instructions with, tool components, reamer, and flex hone. $25 - another bargain that will save you grief. SL-782B - Alternate Means of Compliance to SL-782.
We can thank our fellow Comanche enthusiast Mr. Wilcox for his efforts to correct this oversight. Reasoning: the AD 77.13.21 stated SL-782, not and not., from Kah-li-forn-yah he's on the right - you're left - in the photo, has produced and sells a DVD covering the inspection portion of the above AD.
Boy am I a lousy photographer, I'll get a better one when he's not looking; sorry Hans. Drag Links exchange program. Overall this is related to the AD 77.13.01, Part A.
Specifically I have removed this AD service from the list of Migrant Worker services; it has been just too involved for me to deal with in a remote location without the proper equipment that is required to perform this service. However I'm still developing the components program; it's going to be quite an involved project but may also be a real time-saver if you do not have an experienced shop available to perform this service. This service will have the option of cadmium plated steel components, see below. Stay tuned or call for an update. Click on the photo above for a description of which airframes this component fits.
I bought all of Piper's inventory; if you need a new one call me. See also the parts link.
No used serviceable available at this time. I also have cadmium plated serviceable links for the heavy airframes; 260C P/N 25046-000, 400 P/N 22577-000, and twins P/N 22577-000 and 25046-000. As of I have 2 of these links remaining; when they're gone that's it until owner-produced. By popular request above is shown a modified insert from a Piper landing gear assembly drawing showing the order of parts in this area. The beveled washers referenced are not used on the 260C, 400, and twin Comanche; those are non-beveled and a different part number.
The notes in RED are mine. A complete compliment of cadmium plated exchange steel components related to the landing gear is usually available; the above is just a sample. This should be considered when refurbishing the wheel wells or other opportunity. Here is a sketch I'm using for reference; it shows the roll pin and drive screw part numbers, and nose gear springs' new part number. I wish this was a better scanned image for you; I can't improve its quality. Side brace support bracket.
Click here for the. S&B Industries repair to a right side 'heavy' strut housing. This repair solves the cracked strut problem; read Click on the photo above to see the opposite view.
I no longer stock these repaired strut housings; I have pissed off Bruce at S&B Industries so you will have to suffer the down-time waiting for him to repair your strut. I do have a pair of the later struts 27053-000 & 27053-001 as used on the latest PA-39, and in the service kits which are NLA. These struts are properly refinished in Matterhorn white and have the correct brackets cadmium plated and new placards included. I have installed the orifice tube which has been disassembled and cleaned, also included is the strut seal kit and cadmium-plated installation hardware. Strut oleo housing; these are sometimes incorrectly called 'Trunnions'.
FYI - the word ' Trunnion' appears one time in each of the Single and Twin Piper Comanche Service Manuals; in reference to a bushing item #31 in the nose gear strut housing. The infamous and how to reduce the probability it will become a large problem.
See the following link immediately below. From Piper assembly drawing showing detail of the bracket installation at the strut housing.
The bracket is the attachment for the MLG assist spring. The MLG assist spring is supposed to be at every bungee change.
It's easy to spot the crack if you know where to look. New and old style strut housings. A really lousy landing makes for a bad day too.
This one was terminal for a 400. Related discussions. V I P down-lock limit switches. I would bet that this down-lock switch adjustment procedure is not well understood; a slight misadjusting here will allow the gear to be un-safe, i.e.
Not 'down and locked' over center. I have encountered this misadjusted condition even on new harness installations; it can lead to a 'gear collapse'. I wish for all to be aware of this so shout it from the rooftops. Landing Gear - “latest inspection and adjustment procedure” circa 1959. The amber light is the landing gear gear-up indicator light.
See also '. Resetting the after manual extension - an easy method and explanation. If reading this smokes your circuits don't blame me; it wasn't easy to come up with this solution. See above.
Is this what you call 'Conduit Denial'?. Brake hose routing. See also the discussion about main gear doors in the 'landing gear doors' link. Can the push - pull conduits be?. Here is a cute one sent to me by good-guy Chris Kuyoth.