rebites porcas parafusos cabos aeronauticos

rebites porcas parafusos cabos aeronauticos

(Parte 1 de 7)

1.0 Standard Methods and Practises 26/06/98

Page 1

Please read the following information carefully and refer to it often throughout the building process. It contains information on corrosion protection, drilling, deburring, gusset building etc. Also included is a section on bolt and rivet selection to assist you in areas of the manual where bolt or rivet sizes have not been indicated.

1.1 Metal Surface Preparation Some of our kits include the following chemicals to be used for surface preparation and treatment:

C-2200MET-L-SOL Surface Cleaner EP-420Epoxy Chromate Metal Primer EP-430Epoxy Primer Catalyst

As a protective measure against corrosion, mating metal surfaces should be fully deburred, cleaned with C-20, then coated liberally with epoxy chromate primer. This provides a seal between the surfaces to prevent corrosion and moisture buildup. It is a good practice to coat the end of the rivet on the inside surface after installation.

As an optional measure, the rivets can be dipped in chromate prior to installation. This provides protection inside the hole and seals out moisture. If the airframe is not to be painted be careful to avoid excess chromate on the exterior.

The epoxy primer is to be pre-mixed in accordance with the manufacturers directions as displayed on the containers. It is advisable to mix only the amount you need in a small container each time you work, however, larger amounts can be mixed and reused in a sealable container.

1.2 Drilling Holes

It is good practice to use a #40 drill when doing any assembly- if possible never drill to final hole size until assembly is complete. This allows for any movement between parts or adjustment you may want to make that may cause misalignment of the holes during assembly.

Always use a sharp drill bit as: -A sharp bit will not wander as easily as a dull one.

-You can drill faster with a sharp bit.

-You don’t have to push as hard, risking bending flanges etc.

-Always be careful to drill squarely to the work surface.

-Always make sure when drilling through multiple parts or layers that they are clamped together tightly so as not to move around whole drilling.

-Always debur holes on both sides of each part before final assembly.

1.0 Standard Methods and Practises 26/06/98

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1.3 Bolts

Throughout the building process there will be instances where bolts are used to fasten parts or materials together. In some instances It may be for the builder to determine the correct length of the bolt to be used.

The “Rule of Thumb” for determining bolt length is that the bolt must be long enough to pass through the parts or material being fastened together so that:

1. The threaded part of the bolt is never in shear (no threads are allowed inside hole).

2. No more than three and no less than one thread must be showing when the nut is attached and tightened to the correct torque value.

3. At least on flat washer must be used under the nut and no more than three are allowed.

More precise determinations of Grip Length are found in a number of books including the Standard Aircraft Worker’s Manual.

The following information is provided for reference when using AN grade hardware. Most of the time torque values are done to feel. But this table does provide a good outline. Occasionally bolts, other than a standard bolt will be called out for use in the manual. Please ensure that these bolts are used where called out. The Engineering Department selected these as they provide the strength for the connection where a standard bolt can not provide.

1.4 Standard Torque Table (Inch Pounds) * Fine Thread Series

Bolt SizeStandard NutsShear Nuts (MS20365, AN310, AN315)(MS20364, AN320, AN316, AN23-31)

1.0 Standard Methods and Practises 26/06/98

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Coarse Thread Series

Bolt SizeStandard NutsShear Nuts (MS20365, AN310, AN315)(MS20364, AN320, AN316, AN23-31)

* The above calculations were obtained from the Standard Aircraft Handbook.

Figure 1.4.1

AN bolts may be obtained in the following materials. The coding symbols shown follow the basic dash number and identify the material required in the callout. Figure 1.4.1 shows how the material of the bolt may be distinguished by bolt head markings.

( - ) = Steel, cadmium plated C=Corrosion resisting steel D=Aluminum alloy

Example: AN4 - H10A

AN - Army Navy Standard 4 - Diameter in 1/16 inch increments or 1/4 inch diameter ( - ) - Steel, cadmium plated H - Bolt with drilled head and shank required; leave off if plain head required 10 - Refer to table 1 for bolt length and bolt thread corresponding to “10” A - The adding of the letter A indicates that the cotter pin hole is not required

1.0 Standard Methods and Practises 26/06/98

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Note: To determine grip length, deduct the figure indicated below from the lengths shown in table 1.

AN3 - 13-32AN8 - 25-32AN14 - 1-1/4 AN4 - 15/32AN9 - 29-32AN16 - 1-3/8 AN5 - 17/32AN10 - 61/64AN18 - 1-1/2 AN6 - 41/64AN12 - 1-3/32AN20 - 1-1/16 AN7 - 21/32

1.5 AN3-AN20 Hex Head Bolt Length

TABLE 1 Bolts

1.0 Standard Methods and Practises 26/06/98

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Table 2 Screws Recommended Hole Sizes for Self-tapping Sheet Metal Screws

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Table 3 Clearance Drill Sizes for AN Bolts, Screws and Cotter Pins

Bolt Drill Size Drill Size Drill

(Parte 1 de 7)