<< >> NASA ASRS Report 350563, October 1996

Able flight assist by approach controller when S76 rotary winged traffic declares emergency due to an aircraft equipment problem in IFR flight.

Attributes
ACN	350563
Time
Date	199610
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : lga
State Reference	NY
Altitude	msl bound lower : 3200 msl bound upper : 3200
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90
Operator	general aviation : corporate
Make Model Name	S-76/S-76 Mark II
Operating Under FAR Part	other : unknown
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude descent : intermediate altitude other
Route In Use	arrival : on vectors enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 4900 flight time type : 3500
ASRS Report	350563
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	controller : provided flight assist flight crew : declared emergency other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

On an IFR clearance, climbing through 3200 ft, the pilot's side heading and #2 attitude heading reference system failure indications were displayed on the ehsi EFIS. Reversion to the #1 heading and #1 attitude heading reference system were accomplished. Within approximately 40-60 seconds, the #1 heading and #1 attitude heading reference system failed. The pilot using standby compass and standby attitude direction indicator requested an immediate approach into hpn declaring an emergency since all primary heading sources had failed. ATC expedited our approach but with a strong crosswind in heavy rain, it took quite a bit of correction to finally intercept the localizer and GS. We landed without further incident thanks to the excellent handling from ATC. Through much research with other sikorsky S76 operators with the new litef ahrs optical gyros, and sikorsky aircraft representatives, it was determined that we experienced a magnetic disturbance. It is my honest opinion that litef and sikorsky were negligent by not informing pilots or operators of this possible problem or how to correct it. Since this incident, sikorsky has issued a newly approved flight manual supplement addressing this occurrence and a pilot corrective action to follow.

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Original NASA ASRS Text

Title: ABLE FLT ASSIST BY APCH CTLR WHEN S76 ROTARY WINGED TFC DECLARES EMER DUE TO AN ACFT EQUIP PROB IN IFR FLT.

Narrative: ON AN IFR CLRNC, CLBING THROUGH 3200 FT, THE PLT'S SIDE HDG AND #2 ATTITUDE HDG REF SYS FAILURE INDICATIONS WERE DISPLAYED ON THE EHSI EFIS. REVERSION TO THE #1 HDG AND #1 ATTITUDE HDG REF SYS WERE ACCOMPLISHED. WITHIN APPROX 40-60 SECONDS, THE #1 HDG AND #1 ATTITUDE HDG REF SYS FAILED. THE PLT USING STANDBY COMPASS AND STANDBY ATTITUDE DIRECTION INDICATOR REQUESTED AN IMMEDIATE APCH INTO HPN DECLARING AN EMER SINCE ALL PRIMARY HDG SOURCES HAD FAILED. ATC EXPEDITED OUR APCH BUT WITH A STRONG XWIND IN HVY RAIN, IT TOOK QUITE A BIT OF CORRECTION TO FINALLY INTERCEPT THE LOC AND GS. WE LANDED WITHOUT FURTHER INCIDENT THANKS TO THE EXCELLENT HANDLING FROM ATC. THROUGH MUCH RESEARCH WITH OTHER SIKORSKY S76 OPERATORS WITH THE NEW LITEF AHRS OPTICAL GYROS, AND SIKORSKY ACFT REPRESENTATIVES, IT WAS DETERMINED THAT WE EXPERIENCED A MAGNETIC DISTURBANCE. IT IS MY HONEST OPINION THAT LITEF AND SIKORSKY WERE NEGLIGENT BY NOT INFORMING PLTS OR OPERATORS OF THIS POSSIBLE PROB OR HOW TO CORRECT IT. SINCE THIS INCIDENT, SIKORSKY HAS ISSUED A NEWLY APPROVED FLT MANUAL SUPPLEMENT ADDRESSING THIS OCCURRENCE AND A PLT CORRECTIVE ACTION TO FOLLOW.

Data retrieved from NASA's ASRS site as of July 2007 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.