SERVICING THE P-39 AIRACOBRA WHEELS AND TIRES

the wheels and tires of a plane are a noose only a small part of the actual flying time during landings and takeoffs but for these brief intervals every factor affecting the safety of the pilot and plane was forgiven careful attention in service the wheels and tires are important among these factors and if they show any damage or where they mysteriously to remove a main wheel from the p39 the brakes must first be set or the wheels shot and then the fairing is taken off it is fastened at the hub and up on the strut fort by I yokes here first pull the Cotter key and then back off the high castellated nut sometimes it will be necessary to drive the bolt through for this use only a composition mallet there are two spacer washers between the yolk and the fork be careful not to lose them then the hub nut is turned off it is Cotter key and space with the large washers there is also a spacer water between the fairing and the weeds with this fairing remove the wheel is jack up the jack is put in the position under the fork directly in line with the jack point this point is clearly marked and Jack should only be applied at this point raise the wheel until it is clear of the ground next loosen the three screws which hold the wheel dust cover in place they are turned out far enough to allow the cover to be removed but the screws themselves remain in the cover then remove the bearing dust cap and a full mccotter key on the large axle nut which holds the bearing and wheel on the axle with the nuts turned off remove the retaining ring for the bearing then carefully worked the wheel partly off the actual so that the bearing itself can be taken out wrap the bearing in a cloth and set it aside and now the wheel can be taken off be careful to pull the wheel straight out so as not to damage the actual threat to remove the tire from the wheel all of the air must be let out the removable rim as first work loose you may find it a little stubborn but a few taps with a mallet usually does the trick it is forced down far enough so that the lock ring on the wheel which holds the rim in place can be removed then remove the ring it must be pulled up evenly so as not to bind it should be pulled straight off to remove the tire from the wheeled you will find it easier that is first turned over then applying pressure the bead of the tire is work free the cube is taken out in the tire casing is carefully inspected for internal bruises and cracks and external cuts to replace the view that must be deflated it is laid into the casing here with the valve stem pointing downwards the wheel is split in place with the hole for the valve stem properly aligned and the tire is set on the wheel the rim is next replaced and the spot for the turndown end that the lock ring are lined up the rim is flipped on and press down so that the lock ring can be said in its groove carefully inspect the turndown end of the lock ring and the groove to be sure there are no burrs or crash the rim is pulled up evenly over the lock ring so that has fit into the groove on the inside of the rim this locks the rim in place check the valve stem for proper position and the tire is ready to be inflated to the proper pressure before the wheel is replaced the bearing must be carefully cleaned with carbon tetrachloride thoroughly clean as well the brake disc gloss on the wheel removing all dirt and grease the brakes here are a series of friction discs some stationary which fastened to the axles alternating with others that rotate with the wheels these must be lined up with a straight edge so that they will slide into the slots on the inner rim of the wheel inspect the assembly carefully at this point to be sure the wheel is home on the housing with no bearing to support the wheel on the axle whole journey against it until the bearing is replaced unwrapped the bearing and inspected for wear than lubricate according to the directions given on the wheel fairing it is important to remember that the proper amount of grease must see you carefully seat the bearing and replace the retaining ring the axle nut is turned down and tightened fully then back it off one Castle asian so that the wheel will turn freely the noise you hear when the wheel revolves is the brake disc turning against each other the Cotter key is fixed and the bearing dust cap replaced the wheel dust cover is replaced lining up the small access door with the valve stem and the three screws are fastened next the facing water is put back and then the fairing is hung the jet can be let down and the operation is completed to remove the nose wheel set the brakes or a chalk the main wheels and jack up the nose of the plane here regulation army air force jacks are used first remove the safety wire which size through the fork and the axle nut then the nut is turned off before the nut is fully back off tap it with a composition mallet driving the axle to the fort so that it can easily be pulled out from the other side support the wheel so that its weight has taken off the axle and the axle can be pulled through whenever parts are removed in the field you will find it saves time and apart to keep them all together in a safe place on either side of the wheel there is a spacer pcs with the rest of the park to remove the tire from the nosewheel first unfasten the dust cover it is in two sections an assassin with three round head screws remove the valve cap and with a pair of pliers holding the valve spam on the flattened side turn out the stem deflating the huge the valves simplest cube is of a special double valve arrangement to prevent loss of air pressures of the tire creep on the rim and damage the scent the top part is a standard valves or at the bottom below the threads which fasten the valve to the cube is a rubber gasket which seals the air vents when the valve is fully tightened down the cube can be inflated only when the stem is backed off at least four turns so that the air coming down to the small holes will enter the fuse is it is not done the rubber valve connection will birth press down on the tire forcing all the air out then unfasten the dolphin which holds the removable rim in place it is secured with a cotter key the cotter he removes the tin can be four cells with the rim down the lock ring similar to that on the main wheel can be taken off lifting straight up the rim is then removed to remove the tire from the wheel the cube must be inflated the valve is replaced and fruit in only three or four turns enough air is pumped into round out the form of the cube so that it will flip over the hub the hug must be forced through the views it's a tight fit and we'll take a little convincing a small box is available will come in handy here to support the tire but two pieces of wood will do just as well then remove the valve once more and forth all the air out so the secure can be removed from the case to replace the Cuban attire for thought all the air and fold it over so that it can be worked into the tire you will find it easier if you stand the tire on edge so that you can work from both sides replace the valve and inflate the pube rounding on its form so that the hub can be inserted then carefully wipe the hub clean it lies in direct contact with a few than any abrasive or foreign substance might result in damage to the Jews the valve which protrudes at an angle must be aligned with the hole in the hub the hub is carefully forced through the center of the huge be sure the valve lines up with the whole when the hub is in place and they are properly aligned remove the valve and insert it through the hole turning it back into place working on the floor once more first replace the rim the holes for the dollop in left lineup set it in place and depressive so that the lock ring can be reset in it through pull the rim up over the lock ring and insert the dowels in it is they feed with a cutter teeth two in place the fumes the valve sin is best reached with an extension pillars the extension is turned on the stem and then the air filler is applied be sure that the valve itself is four turns short of being fully tightened so that the air will enter the huge in place a tube to the proper pressure required for that particular type of tire the extension seller has been removed and the valve Sanders turns down the final four turns feeding the bottom valve safely and then the cat is replaced next refasten the dust covers with a small section over the valve stem so that it may be reached on the wheel is on the swing in order that any peeping of the tire on the rim may be detected an alignment mark is painted across the rim and tire and now the wheel is ready to be put back on the plane the spacers on either side of the wheel must be thoroughly clean they go in dry and any dress or foreign substance will damage the fitting lift the wheel into position lining up the spacers with the four the axle too must be thoroughly cleaned before it is inserted in the fourth the axle nut is turned on and tighten down another Santa safety wire to the fourth using a heavy wire read it through the hole in the nuts and through the hole in the stuff for the wire pulls the nut in a clockwise direction resisting any tendency for the actual not to loose this completes the work on the nose wheel and the deck can be left out