# US 8,740,152 B1 · Rivetless nutplates for aircraft

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- Number: US 8,740,152 B1
- Document ID: US8740152B1
- Status: Granted
- Kind: B1
- Application number: 12/420,742
- Filed: 2009-04-08
- Granted: 2014-06-03
- Earliest claimed: 2008-05-01
- Assignees: Textron Innovations Inc.
- Applicants: Daniel J. Lyon; Ming Kwan Tse
- Inventors: Daniel J. Lyon; Ming Kwan Tse
- Web page: https://patentgrep.com/patent/US8740152B1

## CPC

- B64C 1/1446: {Inspection hatches (for engine cowls B64D29/08)}
- F16B 11/006: {by gluing (gluing of plastics material B29C65/48)}
- F16B 5/02: by means of fastening members using screw-thread ({F16B5/0004 takes precedence}; construction of screw-threaded connections F16B25/00 - F16B39/00)
- Y10T 29/49966: with supplemental joining
- Y10T 156/1798: with liquid adhesive or adhesive activator applying means
- B64C: AEROPLANES; HELICOPTERS
- F16B: DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING (couplings for transmitting rotation F16D)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Methods for attaching a window to an airframe, methods of maintaining structural integrity of an airframe while attaching a window to the airframe, and portions of an aircraft are set forth herein. One method for attaching a window to an airframe comprises the steps of: applying to a bonding surface of a nutplate an adhesive; inserting through an airframe hole a fixture attached to a nut of the nutplate, and applying tension to the fixture to hold the adhesive-coated bonding surface of the nutplate adjacent an interior surface of the airframe; allowing the adhesive to cure; removing the fixture from the nut of the nutplate; and installing a bolt through a hole of a retainer, through the hole in the airframe, and into the nutplate; the retainer being in contact with and securing the window to the airframe. The adhesive is selected such that very specific conditions are met.

## Claims

### Claim 1

A portion of an aircraft, comprising:
an airframe;
a nutplate coupled to the airframe by adhesive;
a retainer coupled to a window; and
a bolt passing through a hole of the retainer, through a hole in the airframe, and into the nutplate to secure the retainer to the airframe;
wherein the adhesive comprises at least one of composition 1 in Table 1 and composition 2 in Table 2:
TABLE 1
composition 1
approximate %
Ingredient
by Wt
Methyl Methacrylate
40-70
Chlorosulfonated Polyethylene
10-30
Acrylic Polymer
5-10
Acrylic Polymer
3-7
Maleic Acid
1-5
Cumene Hydroperoxide
0.5-1.5
2,6-di-tert-Butyl-p-Cresol
0.5-1.5
And
TABLE 2
composition 2
approximate %
Ingredient
by Wt
METHYLENE PHENYLENE ISOCYANATE
35
URETHANE PREPOLYMER
19-23
MDI HOMOPOLYMER
12-16
CALCIUM SODIUM ALUMINOSILICATE
8-12
TALC
8-12
URETHANE PREPOLYMER
3-7
AMORPHOUS SILICA
2-6.

### Claim 2

A method of maintaining structural integrity of an airframe while attaching a window to the airframe during manufacture of an aircraft, the method comprising the steps:
applying to a bonding surface of a nutplate an adhesive;
maintaining the adhesive-coated bonding surface of the nutplate adjacent an interior surface of the airframe; and
allowing the adhesive to cure;
wherein the adhesive is selected such that the nutplate is secured by the adhesive such that:
the bond between the nutplate and the airframe will withstand a bolt-fastening torque of at least 60 inch pounds;
the bond between the nutplate and the airframe will withstand cycling over a temperature range from approximately −55 degrees Celsius to approximately 82 degrees Celsius;
wherein the adhesive comprises at least one of composition 1 in Table 1 and composition 2 in Table 2:
TABLE 1
composition 1
approximate %
Ingredient
by Wt
Methyl Methacrylate
40-70
Chlorosulfonated Polyethylene
10-30
Acrylic Polymer
5-10
Acrylic Polymer
3-7
Maleic Acid
1-5
Cumene Hydroperoxide
0.5-1.5
2,6-di-tert-Butyl-p-Cresol
0.5-1.5
and
TABLE 2
composition 2
approximate %
Ingredient
by Wt
METHYLENE PHENYLENE ISOCYANATE
35
URETHANE PREPOLYMER
19-23
MDI HOMOPOLYMER
12-16
CALCIUM SODIUM ALUMINOSILICATE
8-12
TALC
8-12
URETHANE PREPOLYMER
3-7
AMORPHOUS SILICA
2-6.

### Claim 3 (depends on 2)

The method of claim 2, wherein the adhesive is allowed to cure for at least 15 minutes.

### Claim 4 (depends on 3)

The method of claim 3, wherein the nutplate bonding surface is generally planar.

### Claim 5

A method for attaching a window to an airframe via a rivetless nutplate, comprising:
applying to a bonding surface of the nutplate an adhesive;
inserting through a hole in the airframe an elastomeric fixture attached to a nut of the nutplate, and pulling the elastomeric fixture to apply tension to the elastomeric fixture to hold the adhesive-coated bonding surface of the nutplate adjacent an interior surface of the airframe;
allowing the adhesive to cure;
removing the elastomeric fixture from the nut of the nutplate; and
installing a bolt through a hole of a retainer, through the hole in the airframe, and into the nutplate; the retainer being in contact with and securing the window to the airframe;
wherein the adhesive comprises at least one of composition 1 in Table 1 and composition 2 in Table 2:
TABLE 1
composition 1
approximate %
Ingredient
by Wt
Methyl Methacrylate
40-70
Chlorosulfonated Polyethylene
10-30
Acrylic Polymer - N.J.T.S. Reg No. 800941-5008P
5-10
Acrylic Polymer - N.J.T.S. Reg No. 800941-5007P
3-7
Maleic Acid
1-5
Cumene Hydroperoxide
0.5-1.5
2,6-di-tert-Butyl-p-Cresol
0.5-1.5
And
TABLE 2
composition 2
approximate %
Ingredient
by Wt
METHYLENE PHENYLENE ISOCYANATE
35
URETHANE PREPOLYMER
19-23
MDI HOMOPOLYMER
12-16
CALCIUM SODIUM ALUMINOSILICATE
8-12
TALC
8-12
URETHANE PREPOLYMER
3-7
AMORPHOUS SILICA
2-6.

### Claim 6

A method of maintaining structural integrity of an airframe while attaching a window to the airframe during manufacture of an aircraft, the method comprising the steps of not riveting a nutplate to the airframe, but instead:
applying to a bonding surface of the nutplate an adhesive selected from the group consisting of urethane adhesives and methyl methacrylate adhesives;
maintaining the adhesive-coated bonding surface of the nutplate adjacent an interior surface of the airframe;
allowing the adhesive to cure; and
installing a bolt through a hole of a retainer, through the hole in the airframe, and into the nutplate; the retainer being in contact with and securing the window to the airframe;
wherein the adhesive has a working time of at least 15 minutes; and
wherein the adhesive is selected such that the nutplate is secured by the adhesive such that:
the bond between the nutplate and the airframe will withstand a bolt-fastening torque of at least 60 inch pounds;
the bond between the nutplate and the airframe will withstand cycling over a range of temperatures expected to be encountered by an aircraft in flight;
the bond between the nutplate and the airframe will withstand a push out force of at least one hundred pounds over the range of temperatures; and
the bond between the nutplate and the airframe will withstand flexing of the airframe during pressurization cycles expected to be encountered by the aircraft;
wherein the adhesive comprises the composition in Table 1:
TABLE 1
approximate
Ingredient
% by Wt
Methyl Methacrylate
40-70
Chlorosulfonated Polyethylene
10-30
Acrylic Polymer - N.J.T.S. Reg No. 800941-5008P
5-10
Acrylic Polymer - N.J.T.S. Reg No. 800941-5007P
3-7
Maleic Acid
1-5
Cumene Hydroperoxide
0.5-1.5
2,6-di-tert-Butyl-p-Cresol
0.5-1.5.

### Claim 7 (depends on 6)

The method of claim 6, wherein the range of temperatures is from approximately −55 degrees Celsius to approximately 82 degrees Celsius.

### Claim 8

A method for attaching a window to an airframe, comprising:
applying to a bonding surface of a nutplate an adhesive;
inserting through a hole in the airframe an elastomeric fixture attached to a nut of the nutplate, and pulling the elastomeric fixture to apply tension to the elastomeric fixture to hold the adhesive-coated bonding surface of the nutplate adjacent an interior surface of the airframe;
allowing the adhesive to cure;
removing the elastomeric fixture from the nut of the nutplate; and
installing a bolt through a hole of a retainer, through the hole in the airframe, and into the nutplate; the retainer being in contact with and securing the window to the airframe;
wherein the adhesive is selected such that the nutplate is secured by the adhesive such that:
the bond between the nutplate and the airframe will withstand a bolt-fastening torque of at least 60 inch pounds;
the bond between the nutplate and the airframe will withstand cycling over a range of temperatures expected to be encountered by an aircraft in flight;
the bond between the nutplate and the airframe will withstand a push out force of at least one hundred pounds over the range of temperatures expected to be encountered by the aircraft; and
the bond between the nutplate and the airframe will withstand flexing of the airframe during pressurization cycles expected to be encountered by the aircraft in flight; and
wherein the adhesive has a working time of at least 15 minutes;
wherein the adhesive comprises at least one of composition 1 in Table 1 and composition 2 in Table 2:
TABLE 1
composition 1
approximate %
Ingredient
by Wt
Methyl Methacrylate
40-70
Chlorosulfonated Polyethylene
10-30
Acrylic Polymer - N.J.T.S. Reg No. 800941-5008P
5-10
Acrylic Polymer - N.J.T.S. Reg No. 800941-5007P
3-7
Maleic Acid
1-5
Cumene Hydroperoxide
0.5-1.5
2,6-di-tert-Butyl-p-Cresol
0.5-1.5
and
TABLE 2
composition 2
approximate %
Ingredient
by Wt
METHYLENE PHENYLENE ISOCYANATE
35
URETHANE PREPOLYMER
19-23
MDI HOMOPOLYMER
12-16
CALCIUM SODIUM ALUMINOSILICATE
8-12
TALC
8-12
URETHANE PREPOLYMER
3-7
AMORPHOUS SILICA
2-6.

### Claim 9 (depends on 8)

The method of claim 8, wherein the nutplate bonding surface is generally planar.

### Claim 10 (depends on 8)

The method of claim 8, wherein the range of temperatures is from approximately −55 degrees Celsius to approximately 82 degrees Celsius.