Alternate Wire Flammability Test Procedures For Small Wire Test Specimens

1
Alternate Wire Flammability Test Procedures For
Small Wire Test Specimens

• Christopher Bresciano
• 3/20/06

2
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens

• Code of Federal Regulations, 14 CFR 25.869(a)(4)
•   Fire protection systems
• Insulation on electrical wire and electrical
  cable installed in any area of the airplane must
  be self-extinguishing when tested in accordance
  with the applicable portions of part I, appendix
  F of this part.

3
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens
60-Degree Electrical Wire Bunsen Burner Test
Set-up
4
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens

• The Code of Federal Regulations, Part 25, Part I
  of Appendix F states the following with regard to
  wire test specimens used in the 60-Degree Bunsen
  Burner Test for Electric Wire
• Appendix F, Part I(a)(3)(b)(7)
• The upper end of the specimen must pass over a
  pulley or rod and must have an appropriate weight
  attached to it so that the specimen is held
  tautly throughout the flammability test. The
  test specimen span between lower clamp and upper
  pulley or rod must be 24 inches
• Breaking of the wire test specimens is not
  considered a failure.

5
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens

• The Aircraft Materials Fire Test Handbook,
  DOT/FAA/AR-00/12, states the following with
  regard to wire test specimens used in the
  60-Degree Bunsen Burner Test for Electric Wire
• Section 4.4.2 - Specimen Length
• The specimens will be cut to a length of 30
  inches (762 mm). The specimen span between the
  lower clamp and upper pulley or rod will be 24
  inches (610 mm).
• Section 4.8.4 - Wire Breakage
• It will not be considered a failure if the wire
  breaks during the test.

6
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens

• Small Part Exemption does not apply to electrical
  wire
• From Appendix F, Part I(a)(1)(v)
• Except for small parts (such as knobs,
  handles, rollers, fasteners, clips, grommets, rub
  strips, pulleys, and small electrical parts) that
  would not contribute significantly to the
  propagation of a fire

7
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens

• This presents a problem when
• The wire test specimen will not fit in the test
  fixture
• (length is less than 30 inches (762 mm))
• - AND/OR -
• The wire test specimen breaks prior to completion
  of the wire flammability test
• (typically, 26 AWG or smaller)

8
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens

• This situation tends to occur when wire
  flammability testing is required for
• Line Replaceable Units (LRUs)
• In-Flight Entertainment System Equipment (IFE)
• Handsets
• Printers
• Other miscellaneous small electronic equipment

9
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens

• Alternate Test Procedure for Wire Specimens that
  Do Not Fit in the Test Fixture (wire is less than
  30 inches long)
• Attach an alternate wire retention device such
  that the wire specimen will maintain its proper
  orientation in the test fixture
• Alligator clips attached to an appropriate length
  of wire can be used as an alternate wire
  retention device.
• Attach a weight to the alternate wire retention
  device to keep the test specimen taut.

10
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens
Wire
Pulley or Rod
Alternate Wire Retention Device (Alligator Clip)
Weight
Wire Specimen
Alternate Wire Retention Device (Alligator Clip)
Wire
Clamp
Alternate Test Set-up for Wire Specimens that Do
Not Fit in the Test Fixture
11
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens

• Alternate Test Procedure for Wire Specimens that
  Break Prior to Completion of Wire Flammability
  Testing (wire is 26 AWG or smaller)
• Use Nickel Chromium Ribbon as an Alternate Wire
  Retention Device
• Attach a nickel chromium ribbon in the test
  set-up using the same method for placing a wire
  specimen in the test fixture.
• Attach a weight to keep the nickel chromium
  ribbon taut. Keep in mind that too heavy a weight
  will cause the ribbon to break under sufficient
  heat.
• Attach the wire specimen to the nickel chromium
  ribbon using string ties (Dacron). Attach sting
  ties at least 3 inches away from the point of
  flame application, being careful to not interfere
  with the flame. The wire specimen should be
  adjacent and parallel to the ribbon. This should
  allow the flame to be applied to the wire
  specimen for the required time period.

12
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens
Alternate Wire Retention Device (Nickel Chromium
Ribbon)
Pulley or Rod
String Ties (Dacron)
3 inches
Weight
3 inches
Wire Specimen
Clamp
Alternate Test Set-up for Wire Specimens that
Break
13
Alternate Wire Flammability Test Procedures for
Small Wire Test Specimens

• Conclusion
• Alternate test procedures are necessary for wire
  specimens that are too small to fit in the
  60-Degree Bunsen Burner Wire Flammability Test
  fixture and for wire specimens that break prior
  to completion of wire flammability testing.
• Proposal
• Allow industry to submit alternate test
  procedures to FAA Tech Center for evaluation and
  approval.
• Incorporate these proposed alternate test
  procedures into the Aircraft Materials Fire Test
  Handbook, DOT/FAA/AR-00/12.