Method and apparatus for bladder repair during composite part curing

A method of sealing a leak in a hollow internal bladder located within a hollow uncured composite part during cure, wherein the hollow uncured composite part includes composite material wrapped around at least a portion of the internal bladder, the method comprising:

• determining a leak exists in the internal bladder prior to cure temperatures reaching a critical cure stage temperature;
• stopping curing of the uncured composite part prior to temperatures reaching the critical cure stage temperature;
• removing an end fitting from a vent opening of the internal bladder;
• placing a rescue bladder within the internal bladder, wherein the rescue bladder is hollow with two opposing vent openings, an outer surface, and an inner surface;
• sealing the outer surface of the rescue bladder or the end fitting to at least one of an impermeable membrane and a rigid forming tool, thereby sealing the uncured composite part within a chamber cooperatively formed by the impermeable membrane, the rigid forming tool, and the outer surface of the rescue bladder, wherein at least one of the vent opening of the rescue bladder and a vent opening of the end fitting are outward of the chamber;
• and
• curing the hollow uncured composite part under heat and pressure, wherein a pressure differential between atmosphere within the chamber and atmosphere outward of the chamber causes the rescue bladder to inflate and press the internal bladder against an inner surface of the hollow uncured composite part during curing.

A method of sealing a leak in a hollow internal bladder located within a hollow uncured composite part during cure, wherein the hollow uncured composite part is an aircraft stringer and includes composite material wrapped around at least a portion of the internal bladder and placed in a stringer cavity of a rigid forming tool, the method comprising:

• determining a leak exists in the internal bladder prior to cure temperatures reaching a critical cure stage temperature;
• stopping curing of the uncured composite part prior to temperatures reaching the critical cure stage temperature and prior to placing the rescue bladder within the internal bladder;
• placing a rescue bladder within the internal bladder, wherein the rescue bladder is hollow with two opposing vent openings, an outer surface, and an inner surface, wherein a rescue bladder stiffener is located within the rescue bladder;
• sealing the outer surface of the rescue bladder or an end fitting fluidly coupled with at least one of the vent openings of the rescue bladder to at least one of an impermeable membrane and the rigid forming tool, thereby sealing the uncured composite part within a chamber cooperatively formed by the impermeable membrane, the rigid forming tool, and the outer surface of the rescue bladder, wherein at least one of the vent opening of the rescue bladder and a vent opening of the end fitting are outward of the chamber;
• and
• curing the hollow uncured composite part sealed within the chamber under autoclave heat and pressure, wherein a pressure differential between atmosphere within the chamber and atmosphere outward of the chamber causes the rescue bladder to inflate and press the internal bladder against an inner surface of the hollow uncured composite part during curing.