IN SERVICE FEEDBACK
| Event date : 05 June 2022 | Time : 05:35 UTC |
| Place : Shah Amanat Airport (VGEG) | Aircraft : ATR 42-300 |
1. SERIOUS INCIDENT DESCRIPTION
On 05 June 2022, the ATR 42-300 took-off at 0535 UTC to Cox’s Bazar airport. After take-off, Airport staff informed the Tower that a wheel was found at the end of RWY 05 at 0539 UTC
Meanwhile, the air traffic controller informed the PIC at 0540 UTC that they found a wheel beside the runway 05 after the departure of the flight. The landing gear of the aircraft retracted normally during take-off and there was no abnormality felt during the take-off. The flight crew decided to proceed to Cox’s Bazar airport as the maintenance base of the company was there.
Meanwhile, the tower communicated the event about finding the wheel to Cox’s Bazar tower. At this stage, the flight crew were in a doubt as to whether the mentioned wheel belonged to their aircraft or not. The flight crew carried out two low passes with the aircraft landing gear in down position to confirm the status of the landing gear. Tower controller confirmed that the outer wheel (No.1) of left main landing gear was missing but inner (No.2) wheel of the left landing gear was intact.
At this stage, pilot expressed their intention to land at Cox’s Bazar airport and requested to arrange for all emergency assistance available for landing.
The aircraft made a safe landing at 0636 UTC.
2. DOMAGE TO AIRCRAFT
Damage was observed on:
- Hub Locking bolt broken into 2 pieces.
- Roller Bearing.
- Left wheel axle (Scratch marks were found on the shinning portion)
Detachment of the outer wheel assembly from the wheel axle
3. FINDINGS
The aircraft was kept under storage with limited preventive maintenance, from September 2016 to May 2018.
The wheel assembly was removed from aircraft as serviceable condition and was kept in store from April 2018 until June 2020. No documentation was found about the wheel bearing greasing during this period.
This wheel was installed in the aircraft on June 2020 and was removed from the aircraft as unserviceable on August 2020 and was returned to store. The store could not produce any document as to how this unserviceable wheel was made serviceable. The aircraft maintenance organization could not show any document asked by the investigation board as to how this wheel was made serviceable, when it was installed in the aircraft and in which date.
4. CONTRIBUTING FACTORS
Improper or no maintenance was carried out for the lubrication of the main landing gear wheel bearing, axle etc during the long/ short term preservation of the aircraft and when the wheel assembly was kept in the store for about 2 years. This improper/ no maintenance contributed to the formation of corrosion in static condition and ultimately contributed to this serious incident.
5. SAFETY RECOMMENDATIONS (FROM THE FORMAL INVESTIGATION)
Intermediate Safety recommendation to the operator:
1- One time inspection is to be carried out to check the condition, especially the presence of corrosion, crack or any other abnormalities to all bearings … This is applicable to all operators of Bangladesh using ATR aircraft in their fleets.
2- The aircraft operating at Cox’s Bazar are more susceptible to corrosion due to salinity. As such a preventive corrosion control program may be introduced in the Aircraft Maintenance Programme (AMP),…This is applicable to all aircraft operating in Cox’s bazar.
Safety recommendation to the operator:
1- Effective supervision and monitoring for field level activities may be introduced by the operator in order to ensure that company policies and procedures are strictly adhered to minimize the gap between field and supervisory level and thereby ensuring safe operation of flight.
2- Perform the lubrication of wheel bearing in accordance with instruction of CMM. To avoid the ambiguity and for more clarity the operator should introduce a local task card on wheel bearing greasing following the procedures in the CMM. This is applicable both for the line maintenance and store.
3- Perform the lubrication of the wheel axle at each MLG wheel installation by performing the task Ref. MP ATR- A- 12-37-32-00ZZZ-720Z-A. While carrying out this task card, also perform the lubrication of wheel bearing as per the CMM. An additional task card for lubrication of wheel bearing may be introduced by the operator.
4- If there is a high number of cycles performed between MLG wheel replacement or long lead time between tire changes, perform the lubrication of the wheel axle by performing the task card Ref. MP ATR-A-12-37-32-00ZZZ-520Z-A and Ref. MP ATR-A-12-37-32-00ZZZ-720Z-A at an interval of 3 months or 600 landing, whichever occurs earlier. While carrying out this task card, also perform the lubrication of wheel bearing as per the CMM. An additional task card for lubrication of wheel bearing may be introduced by the operator.
5- Wash and dry properly the bearing during the inspection process followed by coating of proper grease to avoid corrosion. CMM must be followed during inspection of retaining ring and seals to avoid contamination or condensation within the bearing.
6- In case on the expiry of long-term storage of the aircraft (more than 6 months) in line maintenance or wheel assembly is kept in store with bearing installed condition, the task card MP ATR-A-12-34-30-00ZZZ- 870Z-A is to be followed. In this regard, the operator is required to:
-
- Remove the wheel assembly and inspect the condition of relevant parts of the wheel assembly for defect detection, the condition of grease, corrosion or any other defect;
- Replace the defective parts with serviceable one, in case, if inspection is found to be satisfactory, then lubricate the wheel bearing as per the procedures mentioned in CMM;
- An additional task card may be introduced for clarity and understanding of the maintenance personnel.
7- In case if only bearing is preserved in store, the bearing should be cleaned, dried, coated with a rust preservative and wrapped in protective paper. Once protected, always store the bearing in a dry area until installation to reduce the risk of static corrosion.
8- The store is to be maintained as per the procedures laid down in Maintenance Organization Exposition.
9- the aircraft component is to be procured from authentic sources with back to birth history and as per provision of Maintenance Organization Exposition.
6. ATR RECOMMENDATIONS
LUBRICATION:
- Wheel Bearing:
The lubrication of wheel bearing is usually carried out in shop and it is under wheel manufacturer responsibility, covered by the CMM.
Please refer to OIM 2009/06 Issue 1:
Main and nose wheel bearings failure due to inappropriate maintenance action performed.
- Wheel Axle:
The lubrication of the wheel axle is carried out by performing the task Ref. MP ATR- A- 12-37-32-00ZZZ-720Z-A.
Please refer to OIM 2012/05 Issue 1:
Main and nose wheel loss due to improper installation of the nose wheel.
STORAGE:
- Preparation for immobilization of aircraft:
MP Ref. ATR-A-10-31-XX-00001-810A-A
The aircraft is considered IMMOBILIZED and not STORED when it is immobilized but stays available for use.
– Scheduled immobilization period cannot be more than one month.
– The immobilization clock starts the day of the last flight, and the tasks of this procedure must be performed no later than 7 days from last flight unless differently specified.
When the aircraft is under maintenance/repair status for a duration scheduled lower than one month, it should be put in immobilization status.
- Temporary storage:
MP Ref. ATR-A-10-32-XX-00001-810A-A
It is accomplished when scheduled or chosen aircraft immobilization time (including aircraft under maintenance/repair status) is less or equal to 6 months.
The transition from temporary to extended storage should follow the complete extended storage procedure.
- Extended storage:
MP Ref. ATR-A-10-33-XX-00001-810A-A
It is done when scheduled or chosen aircraft immobilization time (including aircraft under maintenance/repair status) is more than 6 months. It must be decided from the first month of storage.
A part (as a wheel) that is considered “serviceable”, is a part which is in airworthy condition. In the Maintenance procedure, it is instructed to remove the wheel/tire assy and to install “Serviceable” MLG Wheel/Tire Assembly.
MP Ref. ATR-A-10-33-XX-00001-870A-A (Return to Service of Aircraft …)
It means that ATR as well wheel manufacturers, requires that wheel/tire assy that are installed for six months and over (including aircraft storage) should return to the repair loop and re-certification.
7. REPORT
The final report in English is available for download at Final report CAAB Bangladesh
