TUBES, HOSES, AND FITTINGS

Transcription

1 TUBES, HOSES, AND FITTINGS 1. DESCRIPTION This section contains instructions and specifications for aircraft system plumbing and fittings. Page 1

2 2. MAINTENANCE PRACTICES A. Ice Protection System Compression Fittings (See Figure 1) The following procedures are intended for stainless steel and aluminum Ice Protection System Compression Fittings. The fittings covered in this section are intended for use with nylon and stainless steel tubing. Compression fittings covered are 3/16, 5/16, 3/8 and 1/2 sizes. Compression fittings consist of a nut, olive, and o-ring where the nut is tightened to compress the o-ring between the olive and the mating surface. Compression fittings are available in a range of configurations to facilitate assembly of a system; Straight equal fittings where both fitting outlets are the same size are generally used to connect a joint in nylon tubing. Straight unequal fittings are used to connect a joint between two nylon tubes of different size. Equal tees and unequal tees are used in the same way as equal and unequal straight fittings but are configured to accept three tubes. Unequal tees are configured to accept both two small tubes and one larger tube or two large tubes and one smaller tube. Bulkhead fittings are used in the same way as straight fittings or tees except that one side of the fitting has an extended thread which passes through a bulkhead and a lock nut to secure the fitting in position. Compression fittings to equipment on the aircraft are configured to accept one tube. The remaining end of the fitting is screwed into the equipment and sealed with an o-ring seal or bonded seal. The threaded portion of the fitting may have either a parallel thread or a tapered thread. Tubing and compression fittings used on the Ice Protection System are specified in the Illustrated Parts Catalog. With a few exceptions, the use of dissimilar metals within an assembled fitting is to be avoided. CAUTION: When replacing components, cap all supply lines and remake connections as quickly as possible to avoid large amounts of air from entering the system. Procedures for priming the metering pump(s) are described in the Servicing - Metering Pump Procedures as found in the ICE PROTECTION - Distribution Sections of the AMM for the appropriate aircraft configuration; Serials thru w/ Basic Ice Protection: (Refer to 30-05) Serials & subs, 22T-0001 & subs w/ Basic² Ice Protection: (Refer to 30-06) Serials w/ FIKI: (Refer to 30-07) Procedures for removing air from the arterial supply lines and the leading edge panels are described in the Porous Panel Purging procedure as found in the ICE PROTECTION - Distribution Sections of the AMM for the appropriate aircraft configuration. (Refer to 30-00) CAUTION: During disassembly and assembly of compression fittings, apply back torque to fitting nuts to avoid kinking or twisting distribution line. Page 2

3 (1) Disassembly - Ice Protection System Compression Fittings (a) Unscrew the coupling fittings and extract the tubing from fitting. (b) Remove and discard o-ring(s). (c) Inspect existing components for cracks, burrs, corrosion, and wear. Signs of burnishing/ abrasion on the sealing surface are typical and acceptable. Replace damage or worn components as necessary: 1 Slide nut away from the olive. 2 As close as possible behind the olive, cut tubing square to remove damaged olive. 3 If necessary, slide nut off tubing and replace. (2) Assembly - Ice Protection System Compression Fittings (a) Acquire necessary tools, equipment, and supplies. Description P/N or Spec. Supplier Purpose Clenching Tool T A CAV Aerospace Installation of 3/16 O.D. tubing. Clenching Tool T A CAV Aerospace Installation of 5/16 O.D. tubing. Clenching Tool T CAV Aerospace Installation of 3/8 O.D. tubing. Clenching Tool T CAV Aerospace Installation of 1/2 O.D. tubing. Coupling Refer to IPC Cirrus Design Compression Fitting Assembly O-Ring Refer to IPC Cirrus Design Compression Fitting Assembly Olive Fitting Refer to IPC Cirrus Design Compression Fitting Assembly Nut Refer to IPC Cirrus Design Compression Fitting Assembly (b) (c) (d) If disassembly inspection required nut and/or olive replacement: 1 Cleanly cut end of tubing square. 2 Assemble nut and olive onto the tubing Position nut, olive, and nylon tubing to clenching tool and press tubing fully into end of clenching tool. Ensure tubing extends past the olive to the full depth of the clenching tool. Finger tighten compression nut. CAUTION: Note: Do not clench olive with O-Ring installed. It is typical for the torque drag to rise rapidly during olive clenching. (e) Tighten compression nut to the appropriate Tightening Angle. (See Figure 1) (f) Unscrew nut and remove tubing from clenching tool. (g) Perform Inspection/Check - Compression Fitting to ensure olive fitting has been properly clenched. (Refer to ) (h) Reassemble compression fitting. 1 Install new O-Ring. 2 Finger tighten compression nut. 3 Tighten compression nut 180 past finger tight. Page 3

4 (3) Inspection/Check - Ice Protection System Compression Fittings (a) If necessary, place shop towel below compression fitting to catch fluid drip. (b) If necessary, disconnect distribution line from component. (c) Inspection Criteria (See Figure 1) 1 A correctly installed olive will exhibit the following characteristics: Angled sealing surface of olive has signs of burnishing/abrasion; Forward edge of olive is no longer visible and is "curled" into nylon tubing; Nylon tubing exhibits slight flare on the sealing surface side of the olive; Olive is physically secure and does not spin or pull off by hand. 2 An under tightened olive will exhibit the following characteristics: Angled sealing surface of olive has no or insignificant signs of burnishing/abrasion; Forward edge of olive is visible and has not been "curled" into nylon tubing; Nylon tubing does not exhibit a flare on the sealing surface side of the olive; Olive is not physically secure and may spin easily or pull off by hand. 3 An over tightened olive will exhibit the following characteristics: Angled sealing surface concave and signs of excessive burnishing/abrasion; Nylon tubing exhibits excessive flaring on the sealing surface side of the olive. (d) Verify required length of tubing extends beyond end of olive fitting. (See Figure 1) Page 4

5 COUPLING BODY NUT COMPRESSION FITTINGS RECESS TUBE OLIVE NUT TUBE O-RING (NYLON TUBE ONLY) COUPLING BODY O-RING (NYLON TUBE ONLY) OLIVE INSPECTION AND INSTALLATION CRITERIA A UNDER TIGHTENED CORRECT OVER TIGHTENED NYLON TUBING AND ALUMINUM ALLOY FITTINGS TUBE O.D. OLIVE DISTANCE "A" ±0.05" TIGHTENING ANGLE ±30 3/16" 5/16" 3/8" /2" 0.38" 270 NYLON TUBING AND STAINLESS STEEL FITTINGS TUBE O.D. 3/16" 5/16" OLIVE DISTANCE "A" ±0.05" TIGHTENING ANGLE ± STAINLESS STEEL TUBING AND STAINLESS STEEL FITTINGS TUBE O.D. OLIVE DISTANCE "A" ±0.05" TIGHTENING ANGLE ±30 3/16" 270 SR22_MM20_3315 Figure 1 Compression Fittings and Inspection Criteria Page 5

6 B. Hydraulic Fittings (See Figure 2) Hydraulic fittings must be torqued to the following specifications to prevent loosening while in flight, or damage due to over tightening. CAUTION: The tube nut must never be used to pull the tube assembly to seat against the fitting. Page 6

7 Torque for AN-818 Nuts with Steel Tubing Inch-Pounds Nm Minimum Maximum Minimum Maximum -3 3/ / / / / / Torque for AN-818 Nuts with Aluminum oy Tubing Inch-Pounds Nm Minimum Maximum Minimum Maximum -3 3/ / / / / / Torque for AN-818 Nuts with Flexible Hoses Aluminum/Brass Fittings Inch-Pounds Nm Minimum Maximum Minimum Maximum -3 3/ / / / / / Figure 2 Hydraulic Fittings Torque Values (Sheet 1 of 2) Page 7 01 Jan 2016

8 Torque for AN-818 Nuts with Flexible Hoses Steel Fittings Inch-Pounds Nm Minimum Maximum Minimum Maximum -3 3/ / / / / / Torque for Bulkhead Fittings Gasketed Fittings Jamnuts and Fittings without Gaskets Aluminum or Steel Aluminum Steel Minimum Maximum Minimum Maximum Minimum Maximum -3 3/ / / / / / Figure 2 Hydraulic Fittings Torque Values (Sheet 2 of 2) Page 8 01 Jan 2016