After takeoff; first officer's flight director gave erroneous commands with two irus inoperative. Em...

Attributes
ACN	1224463
Time
Date	201412
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Aircraft 1
Make Model Name	B767-300 and 300 ER
Operating Under FAR Part	Part 121
Flight Phase	Cruise Climb
Flight Plan	IFR
Component
Aircraft Component	INS / IRS / IRU
Person 1
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe

Narrative:

After takeoff; first officer's (first officer's) flight director gave erroneous commands and the heading triangle was not displayed on the first officer's nd. The first officer's flight director only gave normal indications when left was selected on his instrument source sel panel. There were no other abnormal indications in the cockpit. No EICAS messages were displayed; no amber lights came on anywhere. After some investigation we discovered there was no information available from the center and right IRU on the IRS mode select panel or either FMC. Concerned that we were operating on only 1 IRU; after consulting with tech and dispatch; we declared an emergency; went direct to ZZZ [our departure airport]. Accomplished QRH overweight landing checklist; made required aml entries.

Original NASA ASRS Text

Title: After takeoff; First Officer's flight director gave erroneous commands with two IRUs inoperative. Emergency was declared and crew returned to departure airport.

Narrative: After takeoff; First Officer's (FO's) flight director gave erroneous commands and the heading triangle was not displayed on the FO's ND. The FO's flight director only gave normal indications when L was selected on his INSTR SOURCE SEL panel. There were no other abnormal indications in the cockpit. No EICAS messages were displayed; no amber lights came on anywhere. After some investigation we discovered there was no information available from the center and right IRU on the IRS Mode Select panel or either FMC. Concerned that we were operating on only 1 IRU; after consulting with Tech and Dispatch; we declared an emergency; went direct to ZZZ [our departure airport]. Accomplished QRH Overweight Landing checklist; made required AML entries.

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.

After takeoff; first officer's flight director gave erroneous commands with two irus inoperative. Emergency was declared and crew returned to departure airport.