Attachment 1 Section 4.pdf

SECTION 4.

Perform the following procedure for inspection of the air flask:

1. Inspect the interior of the air flask for rust. If rust is found or if any damage has been done to the paint, have the air flask sandblasted.

Note: Prior to sandblasting, cap plugs shall be installed to protect the threads.

2. Clean the threads of the air flask by passing a 0.750-16-UNF-2B tap through the flask support’s opening and a 1.62-12-UN-2B tap through the firing valve’s opening.

Note: Air flask certification must be performed by a qualified DOT Hydrostatic Testing Facility.

Note: All testing shall conform to Code of Federal

Regulation (CFR), Title 49, Section 173.34, Qualifications, Maintenance and Use of Cylinders.

Note: The air flask shall be tested in accordance with CFR, Title 49, Section 178.58, Specification 4DA, Welded Steel

Cylinders for Aircraft Use.

Note: Provide plug (7378603) to the hydrostatic testing facility.

3. Have the air flask inspected by a qualified DOT Hydrostatic Testing Facility. In addition, a visual inspection of the air flask, internally and externally, shall be performed in accordance with the Compressed Gas Association’s Pamphlet C-6, Standards for Visual

Inspection of Steel Compressed Gas Cylinders, using the following criteria:

Minimum Allowable Wall Thickness at Manufacture – 0.147 inches

Minimum Allowable Wall Thickness in Service – 0.129 inches

Number of Complete Threads for 0.750-inch hole – five of the first eight threads

Number of Complete Threads for 1.62-inch hole – seven.

Note: The 0.750-in.inch hole has 12 threads but only the first 8 threads (starting from the outside) are engaged by the flask support.

Note: If corrosion and pitting are discovered, ultrasonic testing shall be performed to determine wall thickness.

4. Perform a Water Jacket Test or Direct Expansion Hydrostatic Test in accordance with the Compressed Gas Association’s Pamphlet C-1, Methods for

Hydrostatic Testing of Compressed Gas Cylinders, using the following criteria:

Test Pressure: 4500 psi.

Permanent volumetric expansion may not exceed 10 percent of the total volumetric expansion at test pressure.