B737 captain reported that a rag was observed in a wing flap fairing during preflight.

Narrative:

I was doing the walk-around. I found that there was a red rag jammed into the drain holes of the left inboard flap track fairing. I called operations from my phone while on the ramp and asked if they could send maintenance out to the aircraft as I had found a rag stuck into the flap track fairing. To me it looked like someone might had placed it there to see if it would stay on during flight; either the inbound or outbound. A mechanic came to the aircraft and removed the rag stating that they changed the #1 tire that night and to prevent water from dripping on them while changing the tire; they plugged the flap fairing drain holes with the rag. I would bet it's safe to say that this is not the correct procedure in the aircraft maintenance manual. This rag most likely could have interfered with the flaps during retraction if the rag was to come loose during takeoff.

Original NASA ASRS Text

Title: B737 Captain reported that a rag was observed in a wing flap fairing during preflight.

Narrative: I was doing the walk-around. I found that there was a red rag jammed into the drain holes of the left inboard flap track fairing. I called Operations from my phone while on the ramp and asked if they could send maintenance out to the aircraft as I had found a rag stuck into the flap track fairing. To me it looked like someone might had placed it there to see if it would stay on during flight; either the inbound or outbound. A mechanic came to the aircraft and removed the rag stating that they changed the #1 tire that night and to prevent water from dripping on them while changing the tire; they plugged the flap fairing drain holes with the rag. I would bet it's safe to say that this is NOT the correct procedure in the Aircraft maintenance manual. This rag most likely could have interfered with the flaps during retraction if the rag was to come loose during takeoff.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1573602
Time
Date	201808
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	Flap Fairing
Person 1
Function	Captain
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Total 12065
Events
Anomaly	Deviation - Procedural Maintenance Deviation - Procedural Published Material / Policy