SPORTPLANE BUILDER Tony Bingelis JACKING ...acversailles.free.fr/.../Jacking_aircraft_safely.pdfSPORTPLANE BUILDER Tony Bingelis JACKING AIRCRAFT SAFELY The letter starts out. . .

SPORTPLANE BUILDER Tony Bingelis

JACKING AIRCRAFT SAFELYThe letter starts out. . . "I'm in

need of jacking technique and hard-ware. Basically I need to lift one wheelso I can remove the wheel and tire.What I currently do is 'painful' andtime consuming. Once the aircraft felloff the jack. I use an auto hydraulicjack and a bolt at the aircraft (wing)tiedown hard point. Any (inexpensive)suggestions?"

Sure. Let's explore a few of themore common jacking problems indetail.

Attempting to jack a homebuilt or,for that matter, any aircraft is not dif-ficult and yet it can result, as thisgent learned, in some anxious mo-ments - if not serious consequenceswhen due care is not exercised.

His is not the first airplane to have

The screw jack in use here is normally safer to use than a hydraulic jack becauseit cannot accidentally collapse and allow the aircraft to drop. However, use ofthe wood pad (A), as shown here, is an unsafe practice. If possible always pro-vide a screw-in jack point.

When using hydraulic jacks, you should find some way to lock them in the ex-tended position. This jack is secure against inadvertent collapse with a lockingpin (A) which can be inserted in drilled holes at various levels.

fallen off its jack(s). It is the sort ofthing that can happen in the hangarnext to yours and you may neverlearn about it.

Mishaps like this occur, most un-expectedly, dur ing rout inemaintenance and inspection work.And they have been known to happento experienced aircraft mechanics,and to homebuilders as well. . . moreoften as a consequence of poor jack-ing technique rather than bad luck.

The consequences resulting fromcareless jacking can be devastating.

The worst one imaginable is some-body getting hurt when the aircraftand a poorly placed jack part com-pany.

Almost as bad is the consequenceof a punch hole in the wing when anairplane slips off the jack. This sortof calamity is most likely to happenafter the airplane has been jacked upand somebody is attempting to climbon board, or is doing some sort ofwork that causes the airplane to rock.

SOONER OR LATER YOU'LLHAVE TO DO IT

Jack up your airplane, that is. Thisneed arises anytime you have to:

1. Rotate the tires to reduce tirewear.

2. Replace a worn tire.3. Work on the brakes.4. Lubricate the wheel bearings.5. Repair a flat.6. Adjust wheel alignment.7. Perform a gear retraction test

(that's right, Wilbur, only retracta-bles need this).

WHAT KIND OF JACK?

Aircraft jacks are costly. However,since most of us are not in the main-tenance business, we have no need tospend big bucks on jacks specially de-signed to accommodate a large varietyof heavier aircraft.

The typical homebuil t rarelyweighs over 1200 pounds empty.Jacking such a lightweight object canbe done easily with the smallest ofcommercially available hydraulic or

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LONG RAM HYDRAULIC JACKMIN. HEIGHT 24"

MAX HEIGHT 44 1/2"(3 TON)

DRILL 1/4" BOLT HOLES(3 PLACES)

SMALL BASE MAKES JACKUNSTABLE WHEN FULLY EXTENDED.

FIGURE 1STABILIZING HYDRAULIC JACKS

When an airplane is jacked for anypurpose so that both wheels areoff the ground, it would be wise toplace sturdy supports (saw horses,boxes, barrels, etc.) under thewings . . . just in case. A shophoist can also be used as a safetyprecaution.

Some landing gear axles can ac-commodate a compact 2 tonfloor jack as shown here. Thistype of jack has a lifting range offrom approximately 5" to 21".

mechanical jacks.There are all kinds of

commercial ly availablejacks.

The two most practicalfor our purpose are rela-tively inexpensive. One isa small 2 ton hydraul icjack costing about $12,and the other, a long ram3 ton hydraulic jack pricedas little as $39.99. A goodsource for all kinds of jacksis Harbor Freight Tools ofCalifornia.

The smallest hydraulicjack stocked by most autoparts stores is the common2 ton hydraulic jack oftenselling for less than $15.This size hydraul ic jackcan handle any homebuiltjacking need.

The problem with thesesmall inexpensive jacks,however, is their limitedextension range. Most of

them can raise an object only a mea-ger 5" or so.

Therefore, it will be necessary tobuild some kind of a stand or sturdybox to position your jack up highenough for it to make contact withthe jack point on your aircraft.

In determining how tall to makeyour jack stand, consider sizing it tobe used as close inboard as is practi-cal. This will allow you to make mostof the limited jacking extension thehydraulic jack has for raising a wheeloff the ground.

Another serious shortcoming isthat most hydraul ic jacks have arather small base. This makes themvery unstable and tipsy when ex-tended.

A simple fix for this deficiency is toattach a large base plate (at least 12"x 12") to the bottom of the jack. Ifmade of 3/4" plywood, bolt it througha couple of holes you can drill in thebase of the jack (Figure 1).

A more permanent method wouldbe to arc weld a large 1/4" thick steelplate to the bottom of the jack.

These jack base modifications willdo much to eliminate any tendencyfor the airplane to rock while it isjacked.

JACK POINT LOCATIONSSpecial jacking points can be built

into the fuselage. My Emeraudes had

SPORT AVIATION 75

A single jack can be used for tire rotation. Simply jack one wheel, remove it andlower the axle onto a wood block. The jack can then be removed and reinstalledon the other side to raise that wheel. With both wheels removed, the tire rota-tion can be readily accomplished.

Do not attempt to use a long ram hydraulic jack un-less it has been secured to a large base or modified asthis one has been to ensure stability when extended.

For retraction tests the aircraft must be completely raised from the ground. Toaccomplish this it may be necessary to weigh down the tail. A couple of cinderblocks (A) are loaded onto a tail support stand for this purpose.

handy jack points built into each sideat the firewall.

More common than the fuselagejack points are the jack points com-monly located in the wings of low wingaircraft.

Normal ly , these are the wingtiedown points which double as jackpoints. This change over is accom-plished by removing the tiedown ringand screwing in a short bolt in its placeto serve as a jacking hard point. Toensure greater stability, the bolt head,backed by a jam nut, may be modified.Simply grind the corners of the bolthead to round it off to better fit thejack recess.

Some landing gear legs, such as theCessna spring gear types, can double asjack points. This is accomplished byclamping an adapter, or block, directlyto the gear leg. The jack is then posi-

tioned under it for the jacking.Jack points for a high wing aircraft are more difficult to uti-

lize because the wing is so high above the ground. Special longreach jacks are available, of course, but are very costly. It isprobably more practical to construct a taller stand and use asmaller long ram hydraulic jack.

As the manufacturer of your own homebuilt, it is your re-sponsibility to provide safe jacking points for your aircraft.

BEFORE YOU DO IT

Before jacking, always chock both the front and back sides ofthe opposite wheel tightly! (Figure 2)

Do the same with the tailwheel, or nose wheel if your airplaneis so blessed.

The simplest and safest jacking effort is where only onewheel must be raised off the ground. Fortunately, this allowsyou to accomplish most of your landing gear maintenance needs.

Jacking both wheels at the same time puts you at greater riskbecause you cannot chock the main gear. Nevertheless, you canand should chock the nose wheel or tailwheel as the case may be.

TIRE ROTATION

The jacking problem becomes morecomplicated when you are faced withthe need to "rotate your tires" in an at-tempt to get better wear and a longerlife out of them.

This is because most of us prefer tojack up the entire airplane for the jobso that both wheels are off the ground.

Nevertheless, this is a worthwhileand commendable practice . . . espe-cially if you are the one buying thetires.

Tires usually wear on one side morethan the other. The only thing you cando to minimize this wear is to, occa-sionally, remove both wheels. You canthen demount each tire and turn it

76 NOVEMBER 1994

around on its wheel before reassem-bling it and ins ta l l ing it on theopposite gear leg.

You cannot merely move the rightwheel over to the left gear leg with-out demounting the tire. That tirewould still wear on the same side.You have to disassemble the wheeland turn the tire around on the rimbefore reinstal l ing it in order tochange the wear pattern.

It is also advisable to switch thewheels to the opposite gear legs formore equal tire wear. The reasonfor this is because most pilots, forone reason or other, tend to land(touch down) on one wheel slightlybefore the other.

In my case, I think it is because Itend to look out the left side of theairplane more often and I thereforeseem to touch down on that wheelsooner than on the other.

If you only have one jack, you canstill rotate your tires but it involvesmore work.

1. Jack up one gear and removethat wheel. Then lower the jack toallow the axle to rest on a block ofwood.

2. Next, move the jack over tothe other gear and jack it up so youcan remove that wheel.

3. After completing the tire de-mounting operation just described,you can reinstal l the wheel andlower the jack. Move the jack to theopposite side, jack it up and rein-stall the other wheel to complete thejob.

A FLAT TIRE AND NO JACK . . .

What to do? There you are on anairstrip with no facilities.

Well, for one thing, you have toremove the wheel so you can takethe tube out and get it patchedsomewhere.

The problem is, how do you getthe wheel off if you have no jack andno access to one?

If your airplane is a homebuilt(they are smaller and lighter thanBonanza class store boughts) and itis a biplane or a low wing job youcan substitute a strong back for ajack. The assumption, of course, isthat there is someone else who iswi l l ing to give you a hand (or aback).

Here's where you first learn ifyour emergency tool kit has the

Both are ways to relax after work.

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CHOCKS AREOPPOOIfE WHEEL

CAUSE JACK TO TILT

OPTION ONE

H6CKS

JACK PADM

CKS

(FRONT AND BACK)

OPTION TWO

MODIFIED JACK BASE(SEE FIG. 1)

CHOCKS STURDY SUPPORT

FRONT VIEW

FIGURE 2JACKING TAIL DRAGGERS

tools you need. You do have a smallemergency tool kit, don't you?

In it should be the tools necessary toremove the wheel pants, the axle nutcotter pin, and a pair of slip-joint pliers(vise-grips or monkey wrench) for loos-ening and removing the axle nut.

Next, if possible find a rock or ablock of wood or something you canslip under the axle after the wheel isremoved.

To raise the wheel off the ground isnot difficult if you have someone whois willing to use a little back muscle tobodily raise the wing high enough soyou can slip off the wheel. Preparethe wheel for removal before raisingthe wing.

So much for the strong back jackingtechnique. Replacing the wheel after-

ward is just as simple a procedure.More difficult, probably, would be

locating a tire or a replacement tube ifyou can't effect the neces-sary repair on the spot.

RETRACTION TEST

In performing a retrac-tion test, it will benecessary to weigh downthe tail of the aircraft toget the nose wheel off theground.

An alternate meansis to use a speciallyweighted tail stand thatyou can attach to the tailtiedown ring.

Use whatever means is

dictated by the manufac-turer. If it is a homebuilt,you will have to, in the ab-sence of any guidance,decide which method issafe and suitable for youraircraft.

HOISTING VS.JACKING

Why not hoist the air-plane instead of jacking it?

That is not a good ideafor a number of reasons:

1. You would have toremove the top cowling.

2. When the entire air-craf t is hoisted it isdif f icul t to keep it fromswaying while you are try-ing to work.

3. The hoisting eye onthe engine was not in-tended to support moreweight than just the en-gine. You may over stressand crack the crankcase ifyou try to l i f t the entireairplane from that singlehoisting eye.

If you feel you have tohoist the entire weight ofthe airplane, at least try todistribute the load by in-stalling a second hoistingeye. Use a load levelerarrangement to distributethe weight equally betweenthe two hoisting eyes.

Ordinarily, hoisting theairplane is necessary onlywhen ins ta l l ing and re-

moving the wings - or the landinggear - or maybe loading the airplaneonto a trailer.

What's wrong here? The left wheel is not chockedand the screw jack base looks rather narrow and un-stable.

78 NOVEMBER 1994

There is no harm in using a hoistas a stabilizing safety precautionwhen the aircraft is raised up onjacks.

IN SUMMARYIf you shop around you will find

an amazing variety of jacks (air/hy-draulic jacks , screw jacks , floorjacks, long ram jacks, scissor jacks,etc., etc.) at fairly reasonable prices. . . many of these selling for under$50 can be adapted for your partic-ular need.

Check out your favorite autopar t s place, t ra i le r and campersales outlets, and don't forget Har-bor Freight Tools.

You can save yourself severalhundred dollars by making yourown special jacks for running gearretraction tests . . . assuming youhave such a need. Take two small(2 or 3 ton) hydraul ic jacks andmate them to au tomot ive jackstands as shown in one of the pho-tos and, voila, you are in the hightech jacking business.

As is usually the case, it may benecessary to weight down the tailto get the nose wheel off theground. For this purpose you canmake a steel tail stand that has acouple of angles bolted across thebottom. Connect this stand to thetail tiedown and load it with a cou-ple of cinder blocks to provideenough weight to pull the taildown. This will give you the nosewheel clearance you need.

Hopefully, these jacking sugges-tions wi l l trigger your own ideasand ingenuity for handling yourspecial jacking requirements.

I might add these words of cau-tion:

1. Avoid jacking under windyconditions.

2. Don't trust any jack. Afterraising the aircraft , lock the jackwith some sort of positive lockingdevice.

3. If extensive work is to be done,it would be wise to place a solid sup-port under the raised wing (a sawhorse, crate, barrel. .. whatever).

JACK SOURCES ANDINFORMATION

- Auto Supply Stores- Trailer and Camper Outlets- Harbor Freight Tools, 3491

Mission Oaks Blvd., Camarillo, CA93011-6010, phone 1-800/423-2567(ask for free catalog)

- "Sportplane Construction Tech-niques" by Tony Bingelis (pages260-264, order from EAA)

BOOKS BY TONYThe following books by Tony

Bingelis are available from the EAAAviation Foundation, EAA AviationCenter, Box 3086, Oshkosh, WI54903-3086, 1-800/843-3612.Major credit cards accepted.

If you wish to contact the authorof this column for additional infor-mation, please send a SASE to:

Tony Bingelis8509 Greenflint Ln.Austin, TX 78759

-Sportplane Builders (AircraftConstruction Methods, 320pages) - $19.95

-Firewall Forward (Engine In-stallation Methods, 304 pages)-$19.95.

-Sportplane Construction Tech-niques (A Builder's Handbook,350 pages) - $20.95.

Add $2.40 postage and handling foreach publication ordered... or orderall three for $52.97 plus $6.95postage and handling. Wisconsinresidents add 5% sales tax.

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