This article is based on technical guidance and safety publications from Airbus and additional industry safety reports.

The Hidden Danger in the Gear: Why Wheel Bearing Maintenance Cannot Be Rushed

Aircraft wheel bearings are among the most stressed components in aviation. Despite supporting loads of up to 500 tons and enduring temperature shifts from sub-zero cruising altitudes to the intense heat of braking, they remain largely hidden from view. According to a technical safety publication by Airbus, the failure of these components is rarely due to design flaws but is almost exclusively the result of improper maintenance.

At AirPro News, we have reviewed the latest guidance from Airbus’s “Safety First” initiative, alongside broader industry data, to understand why these small components continue to pose significant risks to flight safety. The consensus across manufacturers and regulators is clear: strict adherence to maintenance protocols is the only barrier against catastrophic failure.

The Mechanics of Failure

The primary cause of bearing failure, as identified by Airbus and industry data, is maintenance error. Specifically, the issues revolve around incorrect torque application, contamination, and inadequate lubrication. Aircraft use “tapered roller bearings” designed to handle both the weight of the aircraft (radial loads) and side-to-side movement (axial loads). When these bearings are mistreated, the consequences are severe.

The “Double-Torque” Procedure

One of the most critical and frequently misunderstood aspects of wheel installation is the torque procedure. According to Airbus technical guidelines, a specific “double-torque” method is required to ensure the bearings are seated correctly without being overtightened.

The process generally involves three distinct steps:

1. Initial Seating: A high torque is applied while rotating the wheel. This step is crucial to “seat” the rollers and eliminate free play.
2. Back-off: The nut is loosened to relieve stress on the components.
3. Final Torque: A specific, lower torque is applied to set the correct “preload.”

The risk lies in the details. If a technician skips rotating the wheel during the initial torque application, the rollers may not align, leading to a false torque reading. This can result in loose bearings that vibrate and wear prematurely, or tight bearings that overheat and seize.

Real-World Consequences

The failure of a wheel bearing is not merely a maintenance inconvenience; it is a direct threat to the structural integrity of the aircraft. When a bearing seizes, it can generate enough friction to weld components together or shear axles, leading to wheel separation.

Airbus and TSB Canada Data

In one notable case study highlighted by Airbus, an A330 aircraft lost a wheel during takeoff. The investigation revealed that a seized bearing destroyed the axle nut, allowing the wheel to eject from the landing gear. This is not an isolated event. Data from the Transportation Safety Board of Canada (TSB) underscores the prevalence of this issue.

“A study revealed 67 occurrences of nosewheel bearing failures on A319/A320/A321 aircraft worldwide between 1989 and 2004.”

— TSB Canada Data

Cross-Fleet Vulnerabilities

While the Airbus “Safety First” article focuses on their fleet, the physics of bearing failure applies universally. Reports from the UK Air Accidents Investigation Branch (AAIB) detail an incident involving a Boeing 737-800 where a seized bearing generated sufficient heat to compromise the chrome plating and base metal of the axle, causing it to fracture.

Similarly, an investigation into an Embraer EMB-145 (registration G-EMBP) found that moisture contamination due to improper seal installation led to severe overheating and subsequent axle failure. These incidents confirm that regardless of the airframe manufacturer, the root causes, contamination and torque errors, remain consistent.

Industry Best Practices

To mitigate these risks, manufacturers and technical organizations like Timken have established “gold standard” maintenance manuals. The following practices are considered non-negotiable for airworthiness:

• Cleaning is Critical: Technicians must remove all old grease. Old lubricant can hide “spalling” (flaking metal) or heat discoloration (blue or straw-colored metal), which are early signs of fatigue and overheating.
• Pressure Packing: Hand-packing grease is often insufficient. Industry standards recommend using pressure packing tools to ensure grease penetrates behind the cage where the rollers contact the race.
• Grease Compatibility: Mixing clay-based and lithium-based greases can cause the mixture to break down, destroying its lubricating properties. Lithium-based grease is generally preferred for its water-repelling capabilities.
• Wheel Rotation: As emphasized in the torque procedure, the wheel must be rotated while tightening the nut to align the rollers.

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The Human Factor in Maintenance

While the technical steps are well-documented, we believe the persistence of these failures points to a human factors challenge. Wheel bearings are “hidden” components; unlike a tire that shows visible tread wear, a bearing often looks pristine until the moment it fails catastrophically. This lack of visual feedback places an immense burden on the maintenance process itself.

In high-pressure line maintenance environments, the requirement to rotate a wheel while torquing it, a process that relies on “feel” and patience, can be a trap for technicians rushing to clear an aircraft for departure. The data suggests that safety in this domain relies less on new technology and more on a disciplined adherence to the basics: cleaning, inspecting, and respecting the torque procedure.

Regulatory Context

Regulators continue to monitor these risks closely. The FAA has previously issued Airworthiness Directives, such as AD 2012-10-09 for Cessna 560XL aircraft, following reports of brake failure linked to loose bearing components. Furthermore, the FAA Safety Team (FAASTeam) frequently issues alerts reminding operators that “grease is not just grease,” warning that using unapproved substitutes constitutes a violation of FAR Part 43.

Whether operating a General Aviation aircraft or a commercial airliner, the message from the industry is uniform: take care of the wheel bearings, and they will carry the load.

Sources

• Airbus “Safety First”: Take Care of the Wheel Bearings
• Transportation Safety Board of Canada (TSB)
• UK Air Accidents Investigation Branch (AAIB)
• Timken
• Federal Aviation Administration (FAA)

This article summarizes reporting by CBS News and Todd Feurer.

Fatal Small Plane Crash Reported at DuPage Airport

Two individuals were killed Wednesday afternoon when a small twin-engine aircraft crashed shortly after takeoff at DuPage Airport in West Chicago, Illinois. According to reporting by CBS News, local authorities and federal investigators responded to the scene immediately following the incident.

The crash occurred at approximately 1:50 p.m. CST on December 17, 2025. Emergency responders found the aircraft in a snow-covered area near the runway, where both occupants were pronounced dead. As of Thursday morning, the identities of the victims have not been released pending notification of their next of kin.

Incident Details and Immediate Response

The aircraft involved has been identified as a Piper PA-30 Twin Comanche, a light twin-engine monoplane often used for personal touring and flight training. Reporting indicates that the aircraft sustained significant front-end damage upon impact. The flight was in its initial departure phase when the accident occurred.

According to CBS News, the West Chicago Police Department and the Federal Aviation Administration (FAA) were among the first agencies to respond. The airport was temporarily closed to facilitate emergency operations and scene documentation.

In a statement regarding the loss of life, the DuPage Airport Authority expressed their condolences:

“Our thoughts are with the families and loved ones of those who lost their lives in this tragic incident.”

Investigation and Environmental Factors

The National Transportation Safety Board (NTSB) has assumed the lead role in the investigation, with support from the FAA. An NTSB investigator was scheduled to arrive at the crash site on Thursday, December 18, to begin the on-scene examination.

Investigators are expected to focus on three primary categories, the pilot’s history and performance, the mechanical state of the aircraft, and the operating environment. While a preliminary report is typically expected within two to three weeks, a final determination of probable cause may take up to two years.

Weather Conditions

Meteorological data from the time of the crash suggests that weather was likely not a primary adverse factor. Conditions at 1:50 p.m. were reported as:

• Sky: Clear
• Visibility: 10 miles
• Wind: Light from the Southeast at 4 knots
• Temperature: Approximately 39°F (4°C)

Despite the clear skies, the ground remained snow-covered from a previous winter storm, which may complicate the physical recovery of debris.

Background: DuPage Airport and the Piper PA-30

DuPage Airport (KDPA) serves as a critical general aviation hub for the Chicago metropolitan area. It is the third-busiest airport in Illinois, handling approximately 133,000 annual operations. The facility relieves traffic from O’Hare and Midway and is frequently used by corporate jets and flight schools.

The Piper PA-30 Twin Comanche was manufactured between 1963 and 1972. It is known for its fuel efficiency and speed but, like many light twin-engine aircraft, requires specific pilot proficiency to manage engine-out scenarios, particularly during the critical takeoff phase.

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The Critical Nature of Takeoff

While it is too early to speculate on the cause of this specific tragedy, the timing of the crash, shortly after takeoff, highlights one of the most dangerous phases of flight. General aviation accident statistics frequently point to the departure leg as a moment of high workload and low altitude, leaving pilots with limited options in the event of a mechanical failure.

With weather conditions reported as clear and calm, investigators will likely scrutinize the aircraft’s maintenance logs and the engine performance during the climb-out. The “routine” nature of the flight, occurring in excellent visibility, underscores the unpredictable nature of aviation incidents.

Sources

• CBS News

This article is based on an official press release from Collins Aerospace (RTX) and supplementary data regarding FAA safety initiatives.

New Software Upgrade Targets “Wrong-Surface” Landings at U.S. Airports

In an effort to mitigate one of aviation’s most persistent safety risks, Collins Aerospace (an RTX business) has deployed a software-based solution designed to alert air traffic controllers when an aircraft lines up to land on the wrong runway, a taxiway, or even the wrong airport. The system, known as STARS Approach Runway Verification (ARV), is now operational at 13 airports across the United States.

According to Collins Aerospace, the technology integrates directly into the Federal Aviation Administration’s (FAA) existing Standard Terminal Automation Replacement System (STARS), the primary platform used by controllers to manage air traffic in terminal areas. By utilizing existing surveillance data rather than requiring new ground hardware, the system aims to provide a rapid, scalable safety net for the National Airspace System.

Addressing a Top 5 Aviation Hazard

The FAA has classified “wrong-surface landings” as one of the top five hazards in commercial and general aviation. These incidents occur when a pilot inadvertently aligns their aircraft with a surface other than their assigned runway. While often corrected before touchdown, the potential for catastrophe remains high, particularly if the mistaken surface is a taxiway occupied by other aircraft.

Data cited in safety reports indicates the scale of the issue. Between 2016 and 2018 alone, there were 596 wrong-surface events recorded in the U.S. National Airspace System. While 85% of these involved general aviation aircraft, commercial carriers are not immune. The development of technologies like ARV was accelerated following high-profile “close calls,” such as the July 2017 incident at San Francisco International Airport where an Air Canada jet nearly landed on a taxiway occupied by four fully loaded passenger planes.

How STARS ARV Works

Unlike systems that rely on new sensors installed on the airfield, STARS ARV is a software modification. It utilizes the radar and ADS-B data already feeding into the control tower. The system creates a geometric “capture box” or cone extending from the runway threshold.

If an approaching aircraft’s track falls outside this safe zone, indicating alignment with a taxiway or a closed runway, for a specific duration, the algorithm triggers a visual and audible alert for the controller. This allows the controller to issue immediate corrective instructions to the pilot.

“Any airport that has STARS can easily adapt and utilize ARV with no additional equipment.”

, Chris Rogers, Director of Automation at Collins Aerospace

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Real-World Success: The Lincoln Airport Incident

The system has already demonstrated its efficacy in live operations. In the fall of 2023 at Lincoln Airport (LNK) in Nebraska, STARS ARV detected a private jet aligned with the wrong runway while the aircraft was still five miles out from the airport.

According to reports on the incident, the system triggered an alert in the tower, allowing the controller to radio the pilot well before the aircraft reached a critical point. Collins Aerospace executives described the event as a “point of pride,” noting that the early warning converted a potential accident into a routine course correction.

Current Deployment and Future Plans

As of 2024, the FAA has deployed the STARS ARV system to 13 locations. These facilities range from major commercial hubs to smaller regional airports where visual confusion, often caused by parallel runways or complex taxiway layouts, can be a significant risk factor.

Confirmed Operational Locations:

• Austin-Bergstrom International (AUS)
• Lincoln Airport (LNK)
• Gerald R. Ford International (GRR)
• South Bend International (SBN)
• Tallahassee International (TLH)
• Cedar Rapids (CID)
• Lansing (LAN)
• DuPage Airport (DPA)
• Chicago Executive (PWK)
• Elkhart Municipal (EKM)
• Elton Hensley (FTT)
• Branson West Municipal (FWB)
• M. Graham Clark Downtown (PLK)

The FAA has included this technology in its broader “Surface Safety Portfolio,” which also includes the Surface Awareness Initiative (SAI) and Runway Incursion Devices (RID). Plans are reportedly in place to expand ARV deployment to dozens of additional facilities throughout 2025.

AirPro News Analysis

The deployment of STARS ARV represents a significant shift in aviation infrastructure strategy: the move toward software-defined safety. Historically, improving runway safety required pouring concrete, installing physical lights, or deploying expensive ground radar arrays (like ASDE-X).

By leveraging the existing STARS hardware footprint, the FAA and Collins Aerospace are demonstrating that legacy systems can be modernized with algorithmic upgrades. This approach is critical for regional and general aviation airports (like many on the current deployment list), which often lack the budget for heavy infrastructure projects but face the same human-factor risks, such as expectation bias, that plague larger hubs. We expect this “software-first” approach to become the standard for future airspace modernization efforts, allowing safety improvements to roll out months or years faster than traditional hardware projects.

Sources: Collins Aerospace, FAA Surface Safety Portfolio