The document discusses the history and methods of aircraft fabric covering. It describes how early coverings used organic fabrics like cotton and linen that were not durable or airtight. Over time, treatments like dope and aluminum pigment were added to fabrics to improve strength and block sunlight. Synthetic materials now provide more resilient options, though some vintage aircraft still use traditional fabrics. The FAA provides approved processes to ensure airworthiness when repairing or recovering aircraft fabrics.

2. INTRODUCTION
 The methods and materials needed to effectively cover
aircraft structures with fabric have improved dramatically
since the early days of aviation. The first practical covering
materials included organic fabrics such as cotton, linen,
and even silk. Although these continue to be used today,
organic fabrics are being replaced with more resilient
synthetic materials. Possessing increased strength and
durability, these products have made fabric covering a
practical means of aircraft construction that will continue to
be used for many years.

3. History
 When early airplanes were constructed using organic fabrics, most builders did
not use any special processes to increase the strength of the material.
 These coverings were not airtight and tended to loosen and wrinkle with
changes in humidity.
 To keep humid air from flowing through the fabric, builders began applying a
rubberized or varnished finish to the covering surface.
 Although such finishes were effective, it was found that shrinking the fabric by
brushing or spraying it with banana oil and collodion and letting it dry provided
better dimensional stability.

4. History
 Later, an improved cellulose nitrate material consisting of cotton fibers
dissolved in nitric acid was used to form a clear dope that could be worked into
the fabric to produce a stronger and more durable finish.
 The cellulose content of cotton fiber is 90%

5. History
 However, when an aircraft structure was covered with white cotton fabric and
coated with the cellulose nitrate dope
 the covering became translucent, exposing the interior framework.
 Over time, it was found that the translucency caused deterioration of the fabric
and interior components due to the sun's ultraviolet rays.

6. History
 To improve durability, manufacturers applied colored enamel over doped fabric to
block the sunlight.
 Enamel paint is paint that air dries to a hard, usually glossy, finish, used for coating
surfaces that are outdoors or otherwise subject to hard wear or variations in
temperature.
 Although this technique provided increased protection, the paint finish tended to
crack and peel due to the lack of adequate adhesion to the dope coating.
 Further improvements led manufacturers to blend fine aluminum powder directly into
the dope before it was applied to the fabric.
 The Aluminum powder may be a thermoplastic or a thermoset polymer. It is
usually used to create a hard finish that is tougher than conventional paint.
 This technique caused the dope to take on a silver color that blocked the sunlight
and also tended to reflect heat away from the fabric.

7. History
 The process of aluminum pigmenting proved effective, but there were still
serious problems with the early style dopes. Besides the problems of organic
decay from sunlight, another major problem associated with cellulose nitrate
dope was its high flammability. In fact, the process of mixing cotton and nitric
acid was similar to a technique used to form guncotton, an explosive used for
the manufacture of smokeless gunpowder. To alleviate some of the fire hazard,
the U.S. Navy developed a cellulose acetate dope for use on their aircraft.

11.  Cellulose acetate dope was later modified to cellulose acetate butyrate (CAB)
dope, which is still widely used today.
 This dope is less flammable, but lacks some of the adhesive qualities of cellulose
nitrate dope. As a result, cellulose nitrate dope is still often used as a base coat
before CAB dope is applied to the fabric. This results in a tradeoff between the
benefits of both materials, but is regarded to be one of the best finishing methods for
organic fabrics.
 However, even with these improvements, fabric-covered construction has been
largely replaced by sheet metal and advanced composite structures. Although the
number of fabric-covered aircraft is relatively small, there are still some airplanes
that are being produced with fabric covering, and many fabric-covered vintage
aircraft continue to remain in service
History

12. Aircraft Fabric Covering
Aircraft dope
 is a plasticized lacquer that is applied to fabric-covered aircraft (both full-
size and flying models). It tightens and stiffens fabric stretched over
airframes, which renders them airtight and weatherproof.
Plasticized
 are additives that increase the plasticity or decrease the viscosity of a
material.
Lacquer
 The term lacquer is used for a number of hard and potentially shiny
finishes applied to materials such as wood.

13. FAA APPROVAL CRITERIA
 Re-covering an aircraft is a major repair in accordance with 14
CFR Part 43 (CODE OF FEDERAL REGULATIONS)
 the details of this type of repair must be recorded on an FAA
Form 337 (Major Repair or Alteration form).
 The process of re-covering or repairing a fabric aircraft must
match the FAA-approved methods and specifications for both
the aircraft type and fabric type.
 There are several FAA-approved methods for covering fabric
and when one of these methods is used, it is important not to
mix or substitute the specified procedures or materials.

14. MANUFACTURER'S SERVICE
MANUAL
 Before an aircraft is certified to be airworthy by the FAA it must
undergo extensive static and flight tests.
 To remain legally airworthy, the plane must be maintained so that it
continues to meet all its original certification requirements.
 Most fabric-covered aircraft manufacturers' service manuals pro-
vide the necessary information to make sure that the same type
and width of fabrics, tapes, threads and stitches are used when
maintaining the covering.

15. SUPPLEMENTAL TYPE
CERTIFICATES
 the FAA-approved procedures for making the
alteration may be contained in a Supplemental
Type Certificate
 If synthetic fabric is to be installed on an aircraft
that was originally covered with an organic mater-
ial ,The FAA issues an STC when an individual or
company shows that the alteration of an aircraft
from its original design still meets FAA criteria for
airworthiness.

16. ADVISORY CIRCULAR 43.13-1B
 If the manufacturer's service manual is not available or does not provide
adequate detail for maintaining the fabric, and an STC is also not available
 FAA Advisory Circular 43.13-1B - Acceptable Methods, Techniques, and
Practices Aircraft Inspection and Repair, may be consulted.
 Chapter 2 of this circular describes in adequate detail an acceptable method of
re-covering an airplane, using cotton or linen fabric with a cellulose dope finish.
 These instructions may be followed about the types of materials, methods of
attachment, and application of finishes for airplanes that were originally certified
with cotton or linen coverings.

17. FAA FIELD APPROVALS
 If it has been determined that a service manual or STC is not available for a
particular fabric covering process, another option for obtaining FAA approval is
to request a one-time field approval.
 In most cases, the closest regional district office of the FAA evaluates and
issues these approvals and authorizes the repair or alteration.

18. FABRIC-COVERING PRODUCTS
 Once it has been decided which approved method would be most appropriate
for a fabric-covering repair or alteration, it is necessary to become familiar with
the products that will be used in the process.
 It is the responsibility of the person making the repair or alteration to verify that
all of the materials to be used meet the airworthiness requirements for the
aircraft.
 In all cases, fabric-covering materials that are used on FAA-certified aircraft
must meet the minimum standards established by the FAA.

19. FABRIC-COVERING PRODUCTS
 To verify that the products meet required specifications, buy them from a
reputable aircraft supply dealer, and confirm that the proper identification is
present on the materials.
 In addition, only use products from the supplier of the specific fabric-covering
process.
 If substitutions are made, there is a possibility that the products may be
incompatible, causing defects in the fabric that ultimately may compromise
safety.

20. PARTS MANUFACTURER
APPROVALS
 When a product such as synthetic fabric or glass cloth is developed for aircraft
applications, the manufacturer must submit data to substantiate that the item
conforms to the standards established by the FAA.
 Once the FAA evaluates the product and verifies that it meets FAA standards,
the manufacturer is granted a Parts Manufacturer Approval (FAA-PMA).
 An FAA-PMA designates that a product is approved by the FAA for use on
eligible type certificated aircraft.
 Once the manufacturer inspects the product for quality control standards, it is
certified as having met the specifications of the PMA.
 Upon final inspection, the product is marked to indicate that it meets the
standards for an FAA-PMA.

23. End of discussion. Thank you for
listening! 

25. AMT612 – 1D
NIÑO JAY R. FRANCISCO
 ACTIVITY NO. 1
 SEATWORK
 ESSAY
 1. WHAT ARE YOUR LEARNINGS IN LESSON 1 –
FABRIC COVERING?`