Rebuild of Carbon Carbon Aircraft Brakes (Heat Sinks)
|Sandwich Method (2 to 1 method) can be used at a later
stage to further increase the useful life. The 2 to 1 method is used for F-16
DESCRIPTION: Heat Sink, Brake Assy, Main Landing Gear, 1 Assy Per Wheel, 2Assys per A/C.
SCOPE : By means of the present method worn out Carbon-Carbon disks are repaired and are rendered Serviceable.
Thickness of new Disks varies as following :
STATORS : 15.8 mm to 19 mm
ROTORS : 18 mm to 19 mm
Circumferentially, the ROTORS feature externally a number of recesses (5 to 9) for their adaptation on corresponding wedges of the Main Landing Gear (MLG) wheel.
STATORS feature internally 6 to 7 recesses for their adaptation on torsion shaft of MLG. Onto all above notches have been nailed suitably shaped metal plates.
Because of repeated use of the Disks, the following deteriorations arise:
1) Decrease of thickness of STATOR or ROTOR Disks by 20 to 25%
2) Enlargement of circumferential recess, and the corresponding apertures of nailing. In all above cases the Disks are rejected as unserviceable.
The present method (patented), as described, includes a method which applied restores to initial values the criteria of deterioration / reject of new Disks, which are possible to re-use.
Restoration of thickness to original values is achieved with smoothing and suitable decrease of thickness of two worn out Disks, their smearing with special covering, placement of one above in the other, their connection and ageing in special oven under suitable conditions of temperature or even pressure. Thickness of final product is that of a new Disk (method two in one).
Re-establisment of worn out regional recess (internal or even external) is achieved by local treatment, insertion of metal additions, opening of extended apertures and corresponding nailing with extended nails. In this way are restored in initial dimensions the deteriorations of recess, and assure equivalent behaviour of Disk with this of one new.
Advandages that are provided by this use of material high cost, and recycling of useful material.
STANDARDS APPLICABLE TO THE HEAT SINKS REBUILD METHOD :
MIL-W-5013 BRAKING SYSTEMS
MIL-Q-9858 QUALITY PROGRAMME REQUIREMENTS
QQ-P-35C PASSIVATION TREATMENT FOR CORROSION RESISTANT STEEL
PROPRIETARY STANDARDS FOR CARBON TREATMENT (COATINGS HEAT TREATMENT).
MIL-STD-889 DISSIMILAR METALS
MIL-STD-1568 MATERIALS AND PROCESSES FOR CORROSION PREVENTION AND CONTROL IN AEROSPACE
WARRANTY: Minimum 300 Landings (Std. A/C Mission Load) O.E.M Landings 300 (Mandatory replacement).
Description of method : The groups of Brakes comprise a sequence of 7 Disks of Carbon–Carbon from which the three ROTORS diameter 322 mm approximately have thickness of 18 mm approximately and their minimal permissible thickness is 14.7 mm approximately.
Regionally they feature 10 shaped metal plates nailed with two nails each (drawing 1, indicator 1). Moreover there exist two STATOR Disks of diameter 290 mm approximately, thickness 19 mm approximately, with minimal permissible thickness 16 mm approximately, and two lateral Disks BACK PLATES or PRESSURE PLATE of same diameter, thickness 14.5 mm approximately, minimal permissible 13 mm approximately.
The STATORS and BACK PLATES feature internally 12 shaped metal plates nailed with a nail each. Provided that one or more Disks are found in the minimal permissible thickness, are applied the process «two in one» reported earlier (drawing 1, indicator 2). Provided that is required, becomes placement extensional nails (drawing 1, indicator 3). Precedes the special covering (drawing 1, indicator 4) and the replacement in special oven.
Reconditioning (rebuild) of heat sinks involves reworking of worn-out areas, application of special cover coats and oven curing and application of French Mod.DF.202 of added stirups. Impregnation Method to increase carbon content is not used because of poor results.