Airfield management: More than FOD

Staff Sgt. Sara Piper, 56th Operations Support Squadron Air Field Management Operations, checks for foreign object debris on the Luke Air Force Base flightline to prevent damage to aircraft. The unit conducts FOD checks every morning around 5:45 a.m. (U.S. Air Force photo/ Airman 1st Class Sandra Welch)

FOE Foreign Object Elimination

Airmen from the 425th Fighter Squadron at Luke Air Force Base prepare F-16 Fighting Falcons to participate in Maple Flag 42 at Cold Lake, Canada. (Photo courtesy of Neil Pearson,

Foreign Object Debris

Team Moody Airmen grab debris off of the flight line during a foreign object debris (FOD) walk, Jan. 2, 2018, at Moody Air Force Base, Ga. The FOD walk was performed following the winter holidays to remove any debris that could potentially cause damage to aircraft or vehicles. (U.S. Air Force photo by Airman Eugene Oliver)

Foreign Object Debris (FOD) is the stuff you see lying on the pavement of a road or a parking lot that most folks would never really pay much attention to. It’s the rocks, roots, sticks and leaves that are part of our everyday lives. FOD poses few problems on the roads and highways, and we’ve all had flat tires from punctures and cracked or chipped windshields from rocks tossed up by the car or truck ahead. While frustrating to pull over to change a tire or call to have a windshield changed, FOD can have a devastating impact on on aircraft of any size.

FOD is estimated to cost the aerospace industry $12 billion per year. $4 billion is the direct cost for damaged parts; however, another $8 billion is consumed in indirect costs such as delays, plane changes, fuel costs, significant damage to aircraft and parts and death and injury to workers, pilots and passengers. (Source: The Economic Cost of FOD to Airlines, Insight SRI Ltd., UK 2008.)

FOD Awareness Saves Lives and Money
FOD Awareness Saves Lives and Money

The Rokap Corporation is dedicated to providing the best quality and highest grade materials in the industry when it comes to fod prevention sings. That is why you only see Rokap signs listed on, They are the Aviation Industries number one choice.

Please View Our (FOD) Signs And Frames Page

Article Highlights


FOD Damages to 737 Flying Controls

Original post courtesy of

The Incident
During routine maintenance of a Boeing 737-838, engineers found metal filings next to the stabilizer trim cable drum in the forward electronics and equipment compartment (located underneath the flight deck).

737 Control Schematic (Credit: TAIC)

While investigating further they found what they described as a cleaning ‘rag’ had been trapped in the windings on the forward cable drum.

The Debris (Credit: TAIC)

This foreign object had caused the stainless steel cable to bulge outward, contact the softer aluminium cable guides and the resulting wear had created the metal filings.

Bulged Cables (Credit: TAIC)

In places the cables had worn right through the tubular aluminium spacer and had started to wear through the harder steel bolts that run through the spacers.

able Guide Steel Bolt Damage (Credit: TAIC)

The Investigation
In their investigation report, issued in March 2015, TAIC state, based on lab tests of the material, that it was “highly likely” the debris originated from the Qantas Sydney maintenance hangar. The ‘rag’ was actually a cellulosic or paper-based fibre and polypropylene material, consistent with one of the disposable tear-off paper roll products used at Sydney.

TAIC concluded that:

The integrity of the aeroplane’s stabiliser trim system manual control was compromised. Whilst considered unlikely, there was the potential for the stabiliser trim system manual control to become jammed or at worst disabled if a cable severed.

Another Incident
Interestingly Melbourne and Auckland sites use fabric rags which, due to their greater robustness, have a far greater potential to cause FOD events, such as jamming bell cranks, or jamming landing gear uplocks. The later was demonstrated by a subsequent incident involving a Jetconnect aircraft that had undergone maintenance at the Qantas Melbourne maintenance hangar in September 2013. TAIC did not investigate this incident but do comment on it:

On 11 September 2013 a Jetconnect B737-838, registration ZK-ZQC, was involved in an incident that occurred during a flight to Wellington. The aeroplane had departed from Melbourne, where it had recently had maintenance carried out on the landing gear. After departing Melbourne the flight crew had difficulty raising the right main landing gear. The right main landing gear initially retracted but did not stay up, falling back down once the gear selector was moved to the off position. When the crew reselected the gear lever to the up position, the right main gear retracted and stayed up. After the aeroplane landed at Wellington the ground engineers inspected the landing gear and found a rag wrapped around the right main landing gear uplock assembly.

Qantas… conducted a safety investigation into the second incident, which found that the rag had been used by an engineer to protect against an accidental head strike on the uplock during a maintenance task in the right main wheel well area. The rag was subsequently left on the uplock assembly after the maintenance task was completed, and it interfered with the retraction of the right main landing gear during the next flight.

Safety Lessons
TAIC make no recommendations but state, fairly self-evidently that the key lesson is that:

… all personnel must take care not to leave anything behind inside an aircraft after completing maintenance or cleaning tasks, especially in areas or near systems critical to flight safety.

This incident does demonstrate that in addition to control of tools other items, such small components, reels of lock wire and consumables, also need to be controlled. One such case involved a bearing element from a roller bearing that jammed a Power Control Unit (PCU) on a Turkish B737-400 in 2009.

The landing gear incident, which is unlikely to have happened with paper based wipe, illustrates the downside of fabric cloth / rags.

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