2025-06 · NASA ASRS report 2257397
Air carrier pilots reported that a logbook entry was not accomplished after the aircraft's brakes were overheated by a previous crew. Maintenance was not present for this aircraft's arrival to inspect the overheated brakes.
Brake Overheat; No logbook entry; systemic issue fleet wide; improper fleet training and guidance to crewsI had a private discussion as well as with the Captain of the flight and it was disclosed to me that one of our aircraft had a severe brake overheat upon landing in ZZZZ; BTMS (Brake Temperature Monitoring System) values reached as high as 7.0 (700º Celsius) on the main wheels; there was no logbook entry by the crew; QRH Procedures were not followed; no inspection (known) to have been performed by ZZZZ maintenance prior to dispatch; and it is assumed that aircraft was subsequently dispatched in non-compliance due to exceeding operational limits.I have recently operated into ZZZZ at maximum landing weights and have verified the safety margins in the landing data which allowed no single brake assembly heating to above a 2.3 BTMS after 15 minutes of landing. A little over a year ago an aircraft that I was riding on suffered a tire failure resulting in substantial damage and out of service of the aircraft for over 2 weeks; and that leads me to writing this report in concert with the above occurrence. That tire failure in ZZZ was precipitated by finding no less than (5) brake overheats and not a single logbook entry by the previous crews. After discovering this I had maintenance in ZZZZ2 perform the BRK TEMP / Brake overheat inspection and no issues were found. However; due to a crew swap I wound up deadheading on the subsequent flight and same aircraft with another crew operating. Long story short despite that maintenance inspection in ZZZZ2; one of the tires suffered a catastrophic failure not of the tire tread but a failure of the internal structural cords in the tire shoulder referred to the engineering manuals as a Shoulder Separation".Shoulder separation is different than a tread separation in that it is caused by repetitive high shear forces (braking without reverse thrust mitigation); translated "braking". After reviewing the engineering documents from the various tire manufacturers; I used a FLIR camera that I have to validate suspicions and determine if in fact our planes are suffering the extreme shear loads that can lead to shoulder separation. On several flights I used idle reverse and flaps 25 to generate high brake temperatures in this case 300ºC (BTMS value = 3) on a 747-400. As I will discuss later this is above the temperature range where "A Special Procedure is required". After landing and 15 minutes of elapsed time; I thermally scanned the main tires; and the data validated the engineering manual predictions as to locations in the tires where the stress is focused and absorbed. No surprise the tire shoulders all showed elevated temperatures; also the tire wall interface too showed elevated temperatures.What is "elevated Temperature"? According [to] the three tire manufacturers 150ºC is considered a tire limit. At 150ºC the tire rubber is approaching a threshold where vulcanization can occur e.g. "Melting" or put another way approaching a "plastic" phase where the tire rather than holding its molded form can become like putty and re-conform to a new shape different than when it was first vulcanized at the factory. Another factor in tire strength is that at 150ºC the rubber composition of the tire can no longer maintain the internal cord structures and now you risk internal separation of the multitude of layers compromising the tires integrity. With each follow-on high energy stop which is defined as any stop where the Brake temperature exceeds 5 (all fleets); the brake manufacturer requires a "High Energy Stop" inspection. A high energy stop is further defined in our manuals where the brake energy exceeds: 400 Fleet = 35;000;000 ft-lbs; 8 Fleet = 34;000;000 ft-lbs Also; anytime the aircraft suffers a "High Energy Stop" it triggers multiple systemic alerts; not only to the crew by way of an EICAS Message "BRK TEMP" which is NOT advisory and has an "associated checklist that requires compliance with additional steps: Refer to the Recommended brake cooling schedule table in the Performance Inflight chapter for the needed cooling time and precautions I will say that this is probably not the best written statement in a checklist; but it is what we have to work with; and it will require "training" to make-up for its shortfall. Again; the next issue is the checklist sends you to the first page which is "advisory Information"; and this is where the vast majority of pilots stop and close the book. This page is simply to determine your "Brake energy" since this is required to determine the precise energy threshold reached by the braking system. However; and since all of our fleet is equipped with a BTMS system pilots can skip this step and move to the next page. It is in this page where our training department seems to completely ignore; check airmen from my experience aren't even familiar with it use or application. The second page is also labeled "ADVISORY INFORMATION"; but this is where the training comes in and which is completely ignored by Flight Ops; Training and line pilots. When you ask a line pilot "What is the maximum temperature of the brakes or predicted BTMS where a special procedure is required" you are reading this probably thinking the same number "5" right?WRONG; the maximum BTMS values before a special procedure is required is:- 2 (-400 Fleet = 15;000;000 ft-lbs and less)- 2.91 (-8 Fleet = 21;000;000 ft-lbs and less)Any value below those thresholds 2 or 2.91 (the predicted and actual BTMS value) there is no special procedure.Further; those energy / BTMS values are temperatures that a maximum weight 747 in its respective fleet should NEVER exceed using "appropriate" stopping techniques Any value above 2 / 2.91 per the performance manuals requires "a special procedure". What is that special procedure? For starters the assumption is that you followed the company guidance and used maximum reverse and appropriate flap settings to mitigate brake temperatures and tire stress. However; the reality is we operate across a myriad of conditions where more energy than what is encountered in "standard conditions" will be exceeded; hence the brake cooling schedule. The brake cooling schedule assumes you fully mitigate thermal stress and brake energy yet due to deferred items like reversers; de-activated brakes etc. brake energy exceeded the normal range. In those cases; the manufacturer lists the option to allow for extended cooling times on the ground OR to leave gear extended when in the air to facilitate brake cooling. However; when you ask just about any line pilot the answer if you get a BTMS of 5 or more that the only consideration is that "the brakes need additional time to cool" often sprinkled with a dose of "they need to cool for 60 minutes". Let's dive into this "60 minutes" why? Because its flat out wrong and will get somebody killed.First off in ANY fleet 747; 767; 777 any BTMS value above 5 and there is NO AUTHORIZED COOLING TIME that may be referred to by the crew…Let me repeat that; there is NO AUTHORIZED COOLING TIME that may be referred to by the crew! If you exceed "5" on the BTMS (35;000;000ft-lbs -400; 34;000;000ft-lbs -8) the aircraft now requires a mandatory inspection for a "High energy Stop" as it's referred to the Maintenance manual. The Pilots QRH states "…the NEEDED cooling time AND precautions"; virtually EVERY pilot; instructor and check airmen glaze over this and head to the hotel once they see those (4) solid black square boxes in the QRH (assuming they even ran it). The devil is in the details; in the "Precautions" you find where pilots get the "60 minutes" reference that seems to circulate on the line. It states: When in the caution zone wheel fuse plugs may melt. Delay Take-off and inspect after one hour. The key phrase is "Delay take-off AND INSPECT AFTER ONE HOUR" Once the plane puts so much energy to drive the brakes to over 500ºCelcius (5 on the BTMS) there is NO AUTHORIZED COOLING TIMES either on the ground OR in the air! Why the mention of the "one hour"? Simple this reference is from the maintenance manual and states "DO NOT APPROACH ANY MAIN WHEEL FOR 60 MINUTES"; why you may ask? Tires have a fuse plug; despite the tires being filled with nitrogen; they do in fact expand due to absorbed heat and energy. That heat and energy causes a rapid rise in tire pressure. Tire pressures are typically in the 220-230 psi range. When a tire assembly reaches 500º C that tire pressure can spike to over 300 psi in as little as 15 minutes. The explosive force in a 747 tire with 300 psi is well north of the energy contained in more than a stick of dynamite. IF the tires wheel fuse plugs fail to melt and deflate the tire; that pressure threshold of 300 psi may lead to an explosive failure of the tire assembly which will absolutely kill and maim anyone in close proximity to the explosion.Maintenance if notified of a "BRAKE OVERHEAT" e.g. "BRK TEMP" EICAS; know that they cannot approach ANY main wheel for at least 60 minutes; and only after that 60 minutes elapses may they conduct the "BRAKE OVERHEAT" /. "HIGH ENERGY STOP" inspection. This is where our crew's knowledge and training have failed them and are exposing multitude of ground crews to EXTREME DANGER. If the Captain fails to notify the ground crews that they have 500ºC brakes or hotter with an associated EICAS (BRK TEMP); they are now exposing all ground personnel to a literal explosion hazard! There are more than 16 tires down there that retain enough explosive force to kill without warning. Captains should be advising the first person on the headset to notify all ground personnel to remain clear of ALL main wheels; and ensure Maintenance is also notified of the hazardous condition to prevent any person(s) from approaching them until the 60 minutes per the Maintenance manual has elapsed. In addition to this notification; the crew MUST MAKE A LOGBOOK ENTRY! The crew has "EXCEEDED THE OPERATIONAL LIMIT" of the brake system; there is an associated EICAS; there is an ASSOCIATE CHECKLIST; there is now an INSPECTION REQURIED of the brake assemblies after one hour has elapsed to mitigate the hazards associated with over-pressure of the tire assemblies. Because crews are ignoring these risk factors because of inadequate and improper training; we are now routinely subjecting all line personnel to hazardous conditions with potential explosive consequences. Crews have normalized the deviation from what is normal to now believing that BRK TEMP EICAS messages are "just an advisory" not realizing the true hazard that lurks among the 16 wheels of the 747.Recommendations: ANY BTMS value above 2.0/2.91 (400/-8) MUST use FULL REVERSE in accordance with the FCTM . ANY BTMS Value above 5: Crews MUST run the BRK TEMP EICAS checklist and refer to the Performance inflight section. MUST be written up in the aircraft logbook. Ground Personnel NOTIFIED to REMAIN CLEAR OF ALL MAIN WHEELS. Maintenance NOTIFIED that the aircraft made a "HIGH ENERGY STOP" driving the maintenance staff to refer to appropriate manuals and procedures. Captains MUST file a report explaining the conditions leading to the Brake Overheat and confirming all precautions were complied with. SMS - (Safety Management System) The company needs to start recording the brake overheats and compile data to mitigate tire stress leading to shoulder separations. SMS - Document the conditions of each brake overheat; Weight; winds; etc. to determine the cumulative energy the fleet is putting into the tires which leads to fatigue of the cord structures and ultimate failure of the tire without any external indications. MAINTENANCE - Mandate that with every ground turn Maintenance MUST review the CMC (Central Maintenance Computer) for present leg faults and there is a stored fault for "BRAKE TEMP" aka "BRAKE OVERHEAT" they will immediately document the discrepancy in the logbook and carry out the High Energy Stop procedures; to incl"
Upon reaching the parking spot in ZZZZ; we received the Brake Temp EICAS message. We ran the Brake Temp checklist and when the ground person connected the headset; the captain told him that we had hot brakes. We were going to make a log book entry after talking with the mechanic; but the mechanic never came to talk to us and we didn't see him after exiting the airplane. We thought that the mechanic would take care of the issue.When the PF sent away for Flaps 25 landing performance; there was a light tailwind (~3 knots). The tower reported 7 knots when they cleared us to land and the CDU (Control Display Panel) progress page showed an 11 knot tailwind. It's possible that on landing we had a little more tailwind compared to when the performance was run. The PF elected to use Max Auto and did use full reverse thrust. As stopping was assured; the PF reduced the reversers to idle but maybe kept the auto brakes on a little longer than necessary. (We rolled from just before Taxiway 1 to the end of the runway at idle and no brakes.)Recommend that the company pages be updated to strongly recommend or require that flaps 30 be used; as it's possible that you will land with a tailwind.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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