Commercial Fixed Wing
Maintenance Airframe; Maintenance Powerplant
Communication Breakdown; Time Pressure; Training / Qualification
Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Aircraft Aircraft Damaged; General Maintenance Action
Equipment / Tooling; Incorrect / Not Installed / Unavailable Part; Human Factors; Procedure
Aircraft was scheduled a Dry Wash per work card. Paperwork was followed however routinely a kit is used that is stored in the hangar bubble. The kit was not available so alternately plastic bags were used to cover entire pitot tubes in 4 locations. Aircraft was secured and vendor began process of dry wash. During the dry wash; different mechanics showed up to run engines for oil service. The engines were run and later it was discovered the plastic had melted to the pitot tubes. Static ports were inspected but no contamination was found. All 4 pitot tubes were documented as contaminated and later replaced. Warning devices and circuit breakers were pulled collared and tagged per work card. (I placed the warning sign in the cockpit to ensure engines and control surfaces are not operated while aircraft is being dry washed.)Routine allowing a pseudo kit to be used and stored in bubble instead of at stores. Also engine run personnel did not follow procedures and follow warning signs.More awareness as to the seriousness of all tasks no matter how trivial they may seem to be even a simple dry wash. Less pressure to perform task quicker.
We were notified that Aircraft X needed to be run for oil servicing because it had exceeded the ground time limit. Mechanic A was left seat and I was right seat.On approach to Aircraft X; located at the Hangar on spot X; we noticed a dry aircraft wash was taking place. We asked the cleaners to suspend their operation for fifteen minutes in order to accomplish the oil service run and they agreed.Mechanic A proceeded to the cockpit while I accomplished the ground inspection of the left and right engines. I made sure the cowl latches were secured; engine pitot tubes were not obstructed; inlet and exhaust were clear and no malfunctions were apparent. I also cleared several pieces of ground debris to prevent accidental ingestion. I also made sure the FWD and AFT cargo doors; fuselage doors; and panels were secured; as well as re-positioning all ground equipment to a safe distance.Upon boarding the aircraft we noticed pitot circuit breakers were pulled and collared; and the yellow caution placard on the center pedestal. Mechanic A called the hangar maintenance office; discussed the current condition of the aircraft and was given permission to proceed with the running of both left and right engines. We accomplished our flight deck safety checks and before starting engines check lists.After the engine runs were completed; upon disembarking the aircraft; there was a distinct odor of burnt plastic coming from the nose area of the aircraft. Upon further inspection; we noticed the plastic bags that were apparently on the AUX right and left pitot tubes had melted. We immediately notified the mechanic working the aircraft.
Maintenance technicians reported aircraft cleaners had used plastic bags as pitot tube covers for a wash which melted during an engine run.