Narrative:

After the completion of the before landing checklist, propellers to maximum RPM, the #1 acw generator faulted. Shortly thereafter, the #1 np went to 105%. We secured the #1 engine and declared an emergency. During single engine operations we were in need of additional power from the right engine to insure safety of the flight. It is possible that we may have gone into the transient limits of the right (operating engine) #2 engine. The aircraft logbook reflects a write-up for the #1 np not responding to power lever or condition lever inputs. However, we indicated to the mechanics working on the aircraft (on the ground) that we may have gone into the overlimits of the #2 engine. One was an inspector and both ATR mechanics. I trusted their professionalism and after being assured that no write-up was necessary, I did not write it up in the logbook. Consequently, I also informed the 2 mechanics' supervisor in san juan at maintenance base of the possibility of an overtorque or an overtemp on the right engine. In my opinion, I did what was necessary in my capacity to insure the safe outcome of flight on dec/xa/99, from sju to eis. We declared an emergency with the beef island tower who later switched us to sju approach who instructed us to hold north over the bfi NDB at 4000 ft. While we were stabilized at 4000 ft we elected to restart the #1 engine while referencing the QRH for the engine restart in flight checklist, which was permitted on the precautionary shutdown checklist if no engine damage was suspected. We felt that there was no damage since the engine gauges had normal readings even when the np showed 105%. It started normally and all parameters showed normal. The previous np problem was no longer present. Given the fuel status of about 1250 pounds (650 pounds per engine), the WX conditions and after having consulted with dispatch, we proceeded to land in tortola. We informed the mechanics that during the emergency we may have entered the transient limits of the #2 engine, but that we could not recollect the exact readings at that time. Every time I was assured that no write-up was necessary and that they would inspect it, a mechanic can also write up a discrepancy in the aircraft logbook. Furthermore, it was explained to us they had equipment that would read the flight data recorder and would show any discrepancies. They ran up the 2 engines at maximum power for about 20-30 mins and did a series of tests. They concluded all their tests and we flew the aircraft back to sju without revenue passenger. However, it is important to remember that according to far 121.557 and 121.559, in an emergency, the captain is authority/authorized to use any airport and to deviate from the prescribed methods, procedures or minimums, in the interest of safety, and to resolve upon a course of action dictated by circumstance.

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Original NASA ASRS Text

Title: AN ATR42 FLC HAS THE #1 GENERATOR FAIL, THE L ENG PROP OVERSPD AND AN INFLT ENG SHUTDOWN S OF TUPJ, VI.

Narrative: AFTER THE COMPLETION OF THE BEFORE LNDG CHKLIST, PROPS TO MAX RPM, THE #1 ACW GENERATOR FAULTED. SHORTLY THEREAFTER, THE #1 NP WENT TO 105%. WE SECURED THE #1 ENG AND DECLARED AN EMER. DURING SINGLE ENG OPS WE WERE IN NEED OF ADDITIONAL PWR FROM THE R ENG TO INSURE SAFETY OF THE FLT. IT IS POSSIBLE THAT WE MAY HAVE GONE INTO THE TRANSIENT LIMITS OF THE R (OPERATING ENG) #2 ENG. THE ACFT LOGBOOK REFLECTS A WRITE-UP FOR THE #1 NP NOT RESPONDING TO PWR LEVER OR CONDITION LEVER INPUTS. HOWEVER, WE INDICATED TO THE MECHS WORKING ON THE ACFT (ON THE GND) THAT WE MAY HAVE GONE INTO THE OVERLIMITS OF THE #2 ENG. ONE WAS AN INSPECTOR AND BOTH ATR MECHS. I TRUSTED THEIR PROFESSIONALISM AND AFTER BEING ASSURED THAT NO WRITE-UP WAS NECESSARY, I DID NOT WRITE IT UP IN THE LOGBOOK. CONSEQUENTLY, I ALSO INFORMED THE 2 MECHS' SUPVR IN SAN JUAN AT MAINT BASE OF THE POSSIBILITY OF AN OVERTORQUE OR AN OVERTEMP ON THE R ENG. IN MY OPINION, I DID WHAT WAS NECESSARY IN MY CAPACITY TO INSURE THE SAFE OUTCOME OF FLT ON DEC/XA/99, FROM SJU TO EIS. WE DECLARED AN EMER WITH THE BEEF ISLAND TWR WHO LATER SWITCHED US TO SJU APCH WHO INSTRUCTED US TO HOLD N OVER THE BFI NDB AT 4000 FT. WHILE WE WERE STABILIZED AT 4000 FT WE ELECTED TO RESTART THE #1 ENG WHILE REFING THE QRH FOR THE ENG RESTART IN FLT CHKLIST, WHICH WAS PERMITTED ON THE PRECAUTIONARY SHUTDOWN CHKLIST IF NO ENG DAMAGE WAS SUSPECTED. WE FELT THAT THERE WAS NO DAMAGE SINCE THE ENG GAUGES HAD NORMAL READINGS EVEN WHEN THE NP SHOWED 105%. IT STARTED NORMALLY AND ALL PARAMETERS SHOWED NORMAL. THE PREVIOUS NP PROB WAS NO LONGER PRESENT. GIVEN THE FUEL STATUS OF ABOUT 1250 LBS (650 LBS PER ENG), THE WX CONDITIONS AND AFTER HAVING CONSULTED WITH DISPATCH, WE PROCEEDED TO LAND IN TORTOLA. WE INFORMED THE MECHS THAT DURING THE EMER WE MAY HAVE ENTERED THE TRANSIENT LIMITS OF THE #2 ENG, BUT THAT WE COULD NOT RECOLLECT THE EXACT READINGS AT THAT TIME. EVERY TIME I WAS ASSURED THAT NO WRITE-UP WAS NECESSARY AND THAT THEY WOULD INSPECT IT, A MECH CAN ALSO WRITE UP A DISCREPANCY IN THE ACFT LOGBOOK. FURTHERMORE, IT WAS EXPLAINED TO US THEY HAD EQUIP THAT WOULD READ THE FLT DATA RECORDER AND WOULD SHOW ANY DISCREPANCIES. THEY RAN UP THE 2 ENGS AT MAX PWR FOR ABOUT 20-30 MINS AND DID A SERIES OF TESTS. THEY CONCLUDED ALL THEIR TESTS AND WE FLEW THE ACFT BACK TO SJU WITHOUT REVENUE PAX. HOWEVER, IT IS IMPORTANT TO REMEMBER THAT ACCORDING TO FAR 121.557 AND 121.559, IN AN EMER, THE CAPT IS AUTH TO USE ANY ARPT AND TO DEVIATE FROM THE PRESCRIBED METHODS, PROCS OR MINIMUMS, IN THE INTEREST OF SAFETY, AND TO RESOLVE UPON A COURSE OF ACTION DICTATED BY CIRCUMSTANCE.

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.