B777 captain reported returning to departure airport after an air duct failure.

Attributes
ACN	1544547
Time
Date	201805
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B777 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Pneumatic Ducting
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument
Experience	Flight Crew Last 90 Days 219 Flight Crew Total 25900 Flight Crew Type 800
Events
Anomaly	Aircraft Equipment Problem Less Severe

Narrative:

We heard a loud bang/boom; also reported by the flight attendants; level at 17000 ft; auto pilot engaged. We returned [to the departure airport] for a safe and uneventful landing after contacting dispatch and giving the flight attendants [a safety briefing]. It turned out to be a broken up and destroyed air duct near the left wheel well.

Original NASA ASRS Text

Title: B777 Captain reported returning to departure airport after an air duct failure.

Narrative: We heard a loud bang/boom; also reported by the flight attendants; level at 17000 ft; auto pilot engaged. We returned [to the departure airport] for a safe and uneventful landing after contacting Dispatch and giving the Flight Attendants [a safety briefing]. It turned out to be a broken up and destroyed air duct near the left wheel well.

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.