Presetting Tool Operation

Flareless Fitting Installation

• Clamp the pre-setting tool or flareless fitting body in a vice
• Slide a nut and then a sleeve onto the tube, ensuring the pilot and cutting edge of the sleeve points towards the end of the tube
• Lubricate the fitting, insert the ram, and tap lightly with a hammer or mallet until the upset flare punch contacts the die blocks and the die blocks are set against the stop plate on the bottom
• Place the tube end firmly against the bottom of the pre-setting tool seat while slowly screwing the nut onto the tool threads with a wrench until the tube cannot be rotated with thumb and fingers
• Tighten the nut to the number of turns specified in the maintenance manual
• After pre-setting, unscrew the nut from the pre-setting tool or flareless fitting body; check the sleeve and tube

Sleeve Inspection

• The sleeve cutting lip should be embedded into the tube's outside diameter between 0.003 and 0.008 in.
• A lip of tube material will be raised under the sleeve pilot
• The sleeve should be bowed slightly
• It may rotate on the tube and have no lengthwise movement
• The sealing surface of the sleeve, which contacts the 24° angle of the fitting body seat, should be smooth, free from scores, and show no lengthwise or circular cracks
• The minimum internal tube diameter should not be less than the value shown in the table

Tube Securing to Airframe

• Use cushioned P clamps to secure the tube to the airframe
• Ensure the tube assembly is properly aligned before tightening the fittings
• Do not pull the tubes into place with torque on the nut
• Rigid tubing expands and contracts under pressure and is subject to vibration, so it should have at least one bend to remove stress

Hose Assemblies and Fittings

• Fabricating hose assemblies requires basic skills and hand tools
• Determine the necessary hose length from the table and diagram
• Add 5%–8% to allow for expansion or contraction from pressure application
• Wrap the circumference of the hose with masking or plastic electrical tape at the cut-off to prevent braid flare-out
• Measure the hose to the required length and cut off the required length, making sure it is square, using a cut-off machine
• Blow the hose clean with filtered shop air after cutting
• Remove the tape and the clamp socket in a vice
• Install the hose end fitting in a twisting, pushing motion until the hose bottoms on the socket shoulder

Hose End Fitting Installation

• Do not over-tighten a vice on thin-walled lightweight fittings
• Assemble the nipple and nut with a standard matching the inside diameter of the hose
• Nipples have three configurations for the hose-to-tube or component surface-sealing portion: flared, flareless, and flanged
• The socket fits over the outside diameter of the hose and secures one end of the nipple to the hose
• The swivel nut or flange secures the other end of the nipple to the mating connection in the fluid system

Pressure Test Stands

• All flexible hose manufactured in the shop must be hydraulic or pneumatic pressure tested prior to installation in the aircraft
• Fabricated hoses must be tested to 1.5 times system pressure
• A new purchased hose from an approved vendor can be operationally checked after installation in the aircraft by using system pressure in lieu of pressure testing

Pre-installation Procedures

• Check hose or hose assembly installations carefully to make sure identification bands and protective closures are present as required after proof pressure testing
• Ensure proper routing and clamping are mandatory
• Look for kinks or twists in the hose
• Observe the lay line, if possible
• A kinked hose or hose assembly must be replaced
• One that is twisted may be relieved by loosening clamps and swivel nuts, and then straightening the hose by hand
• Re-torque the swivel nuts and tighten the clamps