NASA ASRS CALLBACK - Issue 544 (May 2025)

Issue 544 May 2025

Aviation Maintenance Technicians (AMTs) bear the solemn

responsibility of keeping our aircraft safe and airworthy, and on occasion, they assume additional duties during the course of a flight. Operating in what is commonly considered the most hazardous work environment, AMTs guard their own

safety and that of co-workers, crewmembers, and passengers.

Inquisitive and innovative, AMTs often quell threats and hazards before they become incidents and accidents.

In May, we often remember Charles E. “Charlie” Taylor,

the Wright Brothers’ legendary bicycle mechanic, who turned engine mechanic and became the country’s first real AMT. Charlie was born on May 24, 1868 in Cerro Gordo, Illinois. His life is an iconic American story. In his tradition, ASRS honors and thanks all AMTs for their expertise and professionalism in maintaining America’s aircraft.

This month, CALLBACK offers selected incidents that

demonstrate significant impact, positive or negative, that

AMTs can have on all flights. AMTs work tirelessly to mitigate or eliminate real and potential threats. Explore the narratives as you identify the issues and the actions taken by the AMTs involved.

Part 121 – Inflation Protection

Servicing a B767, this air carrier AMT calls for better safety and protections through new or updated functional inflation tools for all Technicians servicing aircraft tires with nitrogen.

nThe tire inflation tools available for use when servicing

tires with nitrogen do not allow for personnel to stand

forward or aft of the tire that is being serviced. The fittingat the end of the hose has to be held onto the inflation valveby hand, thus meaning you have to stand in front of the tireduring servicing. The AMM (Aircraft Maintenance Manual)reference states in a warning that “make sure that theservicing cart and all personnel are forward or aft of the tirebefore you do the servicing procedure. If the wheel comesapart, the pieces can cause damage to equipment and kill orcause injuries to personnel.” The tooling we have doesn’tallow personnel to stand forward or aft of the wheel. I havealways felt uncomfortable using this tooling during this task,and so do several of my fellow colleagues. …the tooling wehave works well when new but with time and use it wears.Suggestion: Buy a different inflation tool that allows staff tostand where the AMM suggests during tire servicing, or keep the current tooling but change the hose, so that you are able screw the end of the hose onto the inflation valve.

Part 91 – Documentation

The time on a life limited repair was exceeded when this corporate medium-large transport was flown without knowledge of the repair. The AMT/Inspector detailed the incident, its resolution, and the strict adherence to procedures that would have prevented this and other incidents like it.

nReleased aircraft for service with exceeded life limited

structural major repair of the R/H aft wing attach fitting

that was previously installed. The repair was unknown atthe time because no record of it was entered in the aircraftmaintenance logs, nor was there a form 337 filed with theF AA. It wasn’t until after the aircraft had been in operationfor one season that an engineering order for the repairwas discovered at the previous owner’ s location during arecords search. The engineering order placed a life limit of500 cycles or 1 year, whichever occurs sooner, on the repairwith 100 hr. recurring visual inspections in the interim.Since its discovery, the repair has been evaluated with adamage tolerance assessment by a Structural DesignatedEngineering Representative and incorporated into ourstructural inspection program. F AR 91.417 states that anylife limited item or item requiring recurring inspection shallbe recorded in the aircraft maintenance records and 91.419requires that owner operator who sells an aircraft to transferthe permanent aircraft records to the purchaser at the timeof sale. I believe the failure to follow these rules by theprevious owner/operator led to the problem we have today.Moving forward, documenting maintenance in accordancewith F AR 91.419(a) in the permanent records such as themaintenance log books and submitting a form 337 wouldappropriately mitigate this problem.

Part 121 – A Professional Referral

An air carrier AMT-qualified Ramp worker described an abnormal condition during pushback. Fortunately, the B777 returned to the gate, Maintenance was summoned, and a more serious incident may have been averted.

A Maintenance Legacy

A Monthly Safety

Newsletter from

The NASA

Aviation Safety

Reporting System

P.O. Box 189

Moffett Field, CA

https://asrs.arc.nasa.govMarch 2025 Report Intake

Air Carrier/Air Taxi Pilots 5,496

General Aviation Pilots 1,660

Flight Attendants 1,635

Military/Other 943

Controllers 425

Mechanics 222

Dispatchers 195

TOTAL 10,576ASRS Alerts Issued in March 2025

Subject of Alert No. of Alerts

Aircraft or Aircraft Equipment 2

Airport Facility or Procedure 16

ATC Equipment or Procedure 14

Other 2

TOTAL 34n Aircraft X landed in ZZZ.… The ramp and flight crew

failed to notice a failed wheel bearing condition at the gate. Since local policy prohibits Maintenance personnel from performing routine Maintenance walk around inspections on turns, there was no Maintenance trained eyes on the aircraft. The aircraft was fueled, and passengers were boarded as normal. As the aircraft was being pushed back on to its next flight, a ramp employee noticed…what looked like smoke coming from the left Main Landing Gear (MLG). The aircraft came back to the gate and Maintenance was called to investigate. The Maintenance crew determined severe bearing failure conditions and took the aircraft out of service. The aircraft was towed to my hangar on 3 MLG tires only. The gate Maintenance crew was directed to remove the number 4 MLG tire for the ramp to move the plane.… Wheel / tire / landing gear failures are becoming a common occurrence. This aircraft was very close to departing again with a severely damaged MLG.…

Part 121 – Treasures Lost

Air carrier AMTs made unusual discoveries performing emergency field service on a B757. Correcting the situation could easily have prevented a serious ensuing incident.

nZZZ [Airport] field serviced the aircraft… Technicians

were awarded emergency field service to ZZZ for aircraft

757-200 left wing dry bay leak. When tank access panel wasopened, a large piece of FOD fell out of hole. Upon furtherinspection of left fuel tank boost pump pickup screen area,more FOD was found; appeared to be absorbent blanketstotaling 4, each with a dimension of approx 32” in lengthand 14” wide. All FOD was removed from tank area. Aftera discussion with Maintenance Control, it was determinedthat an inspection of [center] and [right] main tank beaccomplished. Upon opening [center] tank access panel,inspection of that bay revealed tooling left behind, sometype of pick approx 4” long. Inspection of right main tankdid not reveal any FOD, and boost pump screen pickup areaclean. I would like to add that I have been a technician forover 15 years and over the years have found many items leftbehind by previous tank entries, but by far this discoverywas one of the worst findings. This type of maintenance onour fleet is unacceptable and very concerning, not only tome, but all of us on the tank team. Thankfully this was foundbefore the boost pump pickup screens became blocked,resulting in engine flameout while operation under ETOPS.Suggestion: If this was the result of a third-party contractoror vendor, they too should be held to the same quality controlstandards that all technicians are held to. These clearanceto close protocols are in place for this very reason, and if notfollowed, could result in a much worse outcome.Part 91 – “…Wisdom Listens.” – J. Hendrix

This FBO AMT listened while towing a Piper Seminole. Inquisitive and proactive, the Technician discovered and corrected a serious problem with the wheel assembly.

nDuring tow operations, I had noticed a noise coming from

the left main landing gear. The wheel cover was removed,

and the axle nut was found rolling loose inside of the coverwithout a safety device. I removed the wheel assembly andinspected for damage. Upon inspection I found that bothwheel bearings were damaged. I cleaned and inspectedthe rest of the wheel assembly for any other damage, butno other damage was found. The wheel assembly was thenreassembled with new bearings with appropriate grease, anda new tire tube. The wheel assembly was then reinstalledon the aircraft, and I ensured this time that the axle nut wastightened properly and a correct safety device was installed.

Part 91 – Never a Dull Moment

Attempting the test run to complete a seemingly unrelated repair on a Premier 1 aircraft, this AMT discovered a second problem and a much larger surprise.

nCompany Service Center [was] notified of hydraulic

seal failure on Aircraft X. Company mobile service unit

began addressing/performing maintenance; determininga filter seal located on the hydraulic power unit hadfailed. Company mobile service provider/mechanic, afterassembling the aircraft hydraulic unit [and] prior to testrunning…notices he had left [the] aircraft generator in“ON” position overnight causing aircraft main battery toresult in insufficient voltage to power aircraft. GPU (GroundPower Unit) was then used for unknown attempts for startingright engine. Starting sequence for Aircraft X is 2 attemptsthen 2 hours for cooling prior [to] a third attempt. …mechanic reports right engine N2 only spooling up to 24%N2 after inducing fuel. Company asked company mechanicto perform a borescope to the right engine. The borescopethat Company performed indicated that the #2 turbinewas missing fins to the internal component. …Company 2determined that the engine was to be removed and sent tomanufacturer for repair.

The reports featured in CALLBACK are offered in the spirit of

stimulating thought and discussion. While NASA ASRS does not verify or validate reports, we encourage you, our readers, to explore them and draw your own conclusions.

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