Bugs block EPR probes on B727 at ind.

Attributes
ACN	406281
Time
Date	199806
Day	Thu
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : ind
State Reference	IN
Altitude	agl bound lower : 0 agl bound upper : 2000
Environment
Flight Conditions	Marginal
Aircraft 1
Controlling Facilities	tower : ind
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : initial climbout : takeoff
Route In Use	departure other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 50 flight time total : 2500 flight time type : 50
ASRS Report	406281
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

On climb out after initial takeoff, the captain called for climb power. After setting climb power on the N1 RPM gauges, I noticed that #1 and #3 EPR settings were above normal. The captain also noticed the increased EPR settings as well. We all agreed that the aircraft was sluggish in the climb and that something was wrong with #1 and #3 engines. All crew members decided that the #1 and #3 EPR's were incorrect but investigation gave no answers. Icing was not a factor. We decided to return to the takeoff airport which resulted in an uneventful landing. Further maintenance revealed clogged EPR probes due to insects. When initial takeoff power was set, I scanned the engine instruments and all appeared normal. About V1, the captain stated that the takeoff roll was somewhat long. So I'm not sure when the insects actually got into the EPR probes. The aircraft was flown by another crew without incident just a few hours before. When icing conditions are present, the data computer calculates maximum EPR for takeoff and gives us an N1 RPM setting as a reference in case of iced EPR probes. As this incident shows, ice isn't the only thing that can clog EPR probes. I think we need an N1 reference for all takeoffs. This would give us an accurate indication of engine performance.

Original NASA ASRS Text

Title: BUGS BLOCK EPR PROBES ON B727 AT IND.

Narrative: ON CLBOUT AFTER INITIAL TKOF, THE CAPT CALLED FOR CLB PWR. AFTER SETTING CLB PWR ON THE N1 RPM GAUGES, I NOTICED THAT #1 AND #3 EPR SETTINGS WERE ABOVE NORMAL. THE CAPT ALSO NOTICED THE INCREASED EPR SETTINGS AS WELL. WE ALL AGREED THAT THE ACFT WAS SLUGGISH IN THE CLB AND THAT SOMETHING WAS WRONG WITH #1 AND #3 ENGS. ALL CREW MEMBERS DECIDED THAT THE #1 AND #3 EPR'S WERE INCORRECT BUT INVESTIGATION GAVE NO ANSWERS. ICING WAS NOT A FACTOR. WE DECIDED TO RETURN TO THE TKOF ARPT WHICH RESULTED IN AN UNEVENTFUL LNDG. FURTHER MAINT REVEALED CLOGGED EPR PROBES DUE TO INSECTS. WHEN INITIAL TKOF PWR WAS SET, I SCANNED THE ENG INSTS AND ALL APPEARED NORMAL. ABOUT V1, THE CAPT STATED THAT THE TKOF ROLL WAS SOMEWHAT LONG. SO I'M NOT SURE WHEN THE INSECTS ACTUALLY GOT INTO THE EPR PROBES. THE ACFT WAS FLOWN BY ANOTHER CREW WITHOUT INCIDENT JUST A FEW HRS BEFORE. WHEN ICING CONDITIONS ARE PRESENT, THE DATA COMPUTER CALCULATES MAX EPR FOR TKOF AND GIVES US AN N1 RPM SETTING AS A REF IN CASE OF ICED EPR PROBES. AS THIS INCIDENT SHOWS, ICE ISN'T THE ONLY THING THAT CAN CLOG EPR PROBES. I THINK WE NEED AN N1 REF FOR ALL TKOFS. THIS WOULD GIVE US AN ACCURATE INDICATION OF ENG PERFORMANCE.

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.