A AMM - INSPECTION AFTER BRAKE OVERHEAT

Transcription

1 FED ALL WARNING : ECTION AFTER BRAKE ALLOW BRAKES AND WHEELS TO COOL BEFORE APPROACHING LANDING GEAR. DO NOT APPLY LIQUID OR GASEOUS FIRE ETINGUISHANT ONTO A HOT WHEEL OR BRAKE UNIT, AN EPLOSION COULD RESULT.. Reason for the Job Inspection for damage subsequent to aircrew report of "HOT BRAKES" warning in the cockpit and/or wheel fusible plug(s) melt. - An excessive temperature may be reached after acceleration-stop, emergency brake application, intensive use of brakes or braking control failure. - Brake overheat can result in melting of one or several main wheel fusible plugs with the following consequences : - deterioration of tire in all cases, - possible deterioration of wheel, - overloading of opposite tire which may cause deterioration of same.. Equipment and Materials ITEM DEATION A. Wheel Change Jack - Nose and Main Gear (Tires Inflated) B. Wheel Change Equipment - Nose and Main Gear (Tires Burst) C. Chocks - Main Gear Wheel D. Chocks - Nose Gear Wheel E. Material No. -00 Cleaning Agents (Ref , P. Block 00 ) ) F. Material No. -00 Cleaning Agents (Ref , P. Block 00 ) ) G. Material No. -00 Strippers (Ref , P. Block 00 ) ) H. Material No or Material No. 6-0 Structure Paints 00 ) ) or Structure Paints 00 ) ) (Ref , P. Block (Ref , P. Block Page of

2 ITEM DEATION J. Material No or Material No Referenced Procedures Structure Paints 00 ) ) or Structure Paints 00 ) ) (Ref , P. Block (Ref , P. Block - (Ref , P. Block 00 ) - (Ref. -7-, P. Block 00 ) - (Ref. --4, P. Block 40 ) - (Ref , P. Block 60 ) - (Ref , P. Block 50 ) - (Ref. -4-7, P. Block 40 ) - (Ref. -4-7, P. Block 60 ) - (Ref , P. Block 50 ) Inspection after a Tire Burst or Tread Throw Wheel Replacement Beam Assy - Bogie Wheels Normal Braking Brake Unit Brake Unit Alternate Braking with Anti skid. Procedure A. Job Set-Up () Make certain that landing gear ground safety locks are correctly installed. () Make certain that wheel chocks are positioned at main and nose gear wheels. B. Recommendations () Recommendations following brake overheat (a) If a tire is inflated, do not go near the area around the wheel for about one hour. When you do Page of

3 (b) (c) go near, go from the front or rear and not from the side of the wheel. Unless there is a fire, do not apply the extinguishing agent (liquid, water, mist, foam etc.) with a spray gun onto a hot tire if it is inflated. Do not apply the extinguishing agent directly into the heat pack of the brake or into the wheel. This can cause thermal shock to the stressed parts. Especially, do not use CO as this has a strong cooling effect which is not the same in all areas. It can cause an explosion in the stressed parts. Extinguishant on hot wheels can : - increase the time necessary for the fuse(s) to melt, or - prevent operation of the fuse(s). You must let the brake get cool by itself for at least one hour and use the cooling fans (if installed). NOTE : You can use blowers or air conditioning equipment only after : - the temperature of the fuses decreases (more than one hour after the aircraft stops) or - the fuses are melted. You must not use these if you can see flames or burning ambers. In the event of fire, immediately stop the fire. Do not wait until the tires are deflated. Come near the wheel only from the front or from the rear. NOTE : We do not recommended the use of multipurpose powders as they may be changed into solid or enameled deposit. These agents stop the fire but they decrease the heat dissipation speed. This can cause permanent structural damages at the brake, the wheel or wheel axle. Page of

4 (d) (e) (f) Do not apply the parking brake. Put a warning notice in the cockpit to tell persons not to operate the landing gear control lever. Clean all the parts if extinguishing agents were used. C. General Data for Hot Brakes HOT BRAKES' WARNING IN COCKPIT 60 deg. C CRITERIA TO REPORT FOR TROUBLE SHOOTING temperature differs between brakes on the same gear AND - temperature of one brake is more than or equal to - or - temperature of one brake is less than or equal to - or - difference between L/H and R/H brake average temperature (*) - or 50 deg.c 565 deg.c 60 deg.c 00 deg.c Wheel removal for inspection in workshop and visual inspection of the brake assy on aircraft. Adjacent wheel to be replaced. Removal of wheel and brake assy for inspection in workshop. Removal of axle sleeve for inspection of axle for possible overheating. Adjacent wheel to be replaced if fuse plug melted only. Fuse plug melting and temperature indication less than 565 deg.c Fuse plug melting and/or 565 deg. temperature indication * No cross wind : no differential braking : service braking energy used On A/C Post SB - / E.O / E.A (A00 Wheels and Brakes) Page 4 of

5 D. General Data for Hot Brakes HOT BRAKES' WARNING IN COCKPIT 00 deg. C CRITERIA TO REPORT FOR TROUBLE SHOOTING temperature differs between brakes on the same gear AND - temperature of one brake is more than or equal to - or - temperature of one brake is less than or equal to - or difference between L/H and R/H brake average temperature (*) 50 deg.c 600 deg.c 60 deg.c 00 deg.c Wheel removal for inspection in workshop and visual inspection of the brake assy on aircraft. Adjacent wheel to be replaced. Removal of wheel and brake assy for inspection in workshop. Removal of axle sleeve for inspection of axle for possible overheating. Adjacent wheel to be replaced if fuse plug melted only. 8 deg.c fuse plug melting 00 deg.c fuse plug melting FED ALL * No cross wind : no differential braking : service braking energy used E. Inspection A. Inspection of the Aircraft In case of tire burst : - do the inspection of the aircraft after a Tire Burst or Tread Throw (Ref , P. Block 00 ) ). Inspection of the Wheels and Brakes Page 5 of

6 A. Inspection after wheel fuse plug(s) melt and reported flight compartment indication of brake temperature not more than 565 deg.c A. Inspection after 8 deg.c wheel fuse plug(s) melt () Remove corresponding wheel and adjacent wheel for overhaul (Ref. -7-, P. Block 00 ) )(Refer to manufacturer"s instructions for overhaul procedure). () Examine brake unit for damage or distortion. (Ref. -4-7, P. Block 60 ) ) () Make certain that there is no hydraulic fluid leakage at level of piston, liners, supply lines, self blanking unions () Clean piston housing with a cloth and make certain it is in correct condition (no separation, no blisters). () (c) Make certain that heat pack is serviceable : If damage is found : - Remove damaged brake unit for overhaul (Ref. -4-7, P. Block 40 ) ) (Refer to manufacturer"s instructions for overhaul procedure). B. Inspection after wheel fuse plug(s) melt and/or reported flight compartment indication of brake temperature equal to or more than 565 deg.c Page 6 of

7 B. Inspection after 00 deg.c wheel fuse plug(s) melt. () Remove corresponding wheel for overhaul (Ref. -7-, P. Block 00 ) ) (Refer to manufacturer"s instructions for overhaul procedure). NOTE : If fuse plug melted, also remove the adjacent wheel for overhaul. () Remove brake for overhaul (Ref. -4-7, P. Block 40 ) ) (Refer to manufacturer"s instructions for overhaul procedure). () Remove protective sleeve/brake unit spacer (Ref. -4-7, P. Block 40 ) ). (4) Clean protective sleeve, brake unit spacer and axle with Material No (5) Inspect brake unit spacer internally and externally for discoloration, burned paint and melted cadmium plating (evidenced by presence of shiny particles). (6) Inspect axle protective sleeve externally for absence of deformation cracks, scratches or plating discrepancies (peeling, chrome flaking) (7) Inspect axle protective sleeve internally for scratches, discoloration, burnt paint, blistering and melted cadmium plating evidences (minute drops, pimpled appearance) showing an overheated condition If any of the above damage found: Page 7 of

8 () Replace the protective sleeve (8) Inspect axle externally for traces of impact, scratches or metal pickups and discoloration. According to the results, proceed as follows : (a) Light discoloration - remove discoloration and aluminum paint topcoat with Material No. -00 and inspect green primer for discoloration. (If none present : axle is serviceable providing it passes the internal inspection para. (9)) - If still present proceed to para. (8)(b (b) Heavy discoloration or paint missing : - strip paint and primer with Material No. -00 and inspect cadmium plating for melting (shiny particles, pimpled appearance or areas of bared metal) using a 0 magnifying glass If damage found : Replace the bogie beam (AMM (Ref. --4, P. Block 40 ) ) NOTE : Bared metal not accompanied by adjacent paint discoloration indicates scuffing damage. In this case axle is serviceable providing it passes Page 8 of

9 the internal inspection para. (9) (9) Inspect axle internally for traces of overheating - this inspection is to determine the temperature reached and concentrated inside the axle and therefore the possibility of hydrogen embrittlement caused by melting and diffusion of the cadmium plating. The embrittlement condition is to be checked in examining : (a) The change in coloration of the paint inside the axle (Polyurethane primer paint) : - if the coloration observed inside the axle belongs to range, the axle is still structurally acceptable for further flights. - if the coloration observed inside the axle belongs to axle is no longer structurally acceptable and the bogie beam must be removed and replaced before any further flight (AMM (Ref. --4 ) ). (b) The appearance of the surface for melted cadmium plating evidences (minute drops, pimpled appearance). - inspect the inner surface of the axle for melted cadmium plating evidences (minute drops, pimpled appearance) and NDT check the axle by Page 9 of

10 dye penetrant or fluorescent inspection. If damage or crack found : - the bogie beam must be replaced before any further flight (AMM (Ref. --4 ) ). F. Test Set-Up G. Test () If axles are serviceable restore protective treatment : - polyurethane primer (Mat No. 6-00) or (Mat No. 6-0) - polyurethane top coat (Mat No.6-08) or (Mat No. 6-04) () Replace brake unit as necessary (Ref. -4-7, P. Block 40 ) ). () Install replacement wheels as required (Ref. -7-, P. Block 00 ) ) A. Carry out an operational test of Normal braking system (Ref , P. Block 50 ) ). B. Carry out an operational test of Standby braking system (Ref , P. Block 50 ) ). H. Close-Up () Remove ground handling and maintenance equipment, tools, standard and special tools, together with ground power Page 0 of

11 FED ALL and replenishing equipment, all access equipment and miscellaneous items. (Ref. Fig. 00 ) Figure 00 Figure 00 (Sheet ) Page of