Narrative:

In flight at an indicated sat of -56C the aircraft began accumulating a trace of rime ice (visually detected the ice on the dark grey wing boots). I was flying in IMC with air mass thunderstorms in the vicinity of the aircraft. The radar was functional and was being used to avoid thunderstorms. I was approximately 20 miles west of a north/south running group of non connected but adjacent storms. The wind was about 40 KTS out of the south. I was flying a heading of 180 paralleling the storms. I selected both engine anti ice switches to on due to afm limitation of -40C minimum temp for wing/stab de-ice boot operation. A few minutes later I received an engine 1 TT0 htr fail and engine 2 TT0 htr fail amber cas messages. I immediately requested a descent to FL350 and a minute or two later was cleared to FL350 by ATC.the QRH procedure for this is: icing conditions............................... Exit/avoidi have received this message a few times flying this aircraft. I cycled the east 1 & 2 anti ice off and back on a few times but the message would always return. I was able to exit and avoid icing conditions around 30;000 ft. I continued the descent and landed uneventfully. The OAT was 25C on the ground.this is an ongoing issue with the embraer phenom 100. I reviewed a central maintenance computer (cmc) download file indicting the TT0 probe had iced. The analysis showed that the TT0 probes installed on the inlet of the engines suffered from an ice build up during flight that impacted the TT0 measurement. The fadec software has a new logic that prevents the adverse effects of this erroneous TT0 measurement on the engine thrust by turning off the TT0 heater. This situation is currently annunciated to the pilot via the E1 (2) TT0 heater fail cas message although the TT0 heater itself is not failed. The pilot can distinguish a TT0 heater hardware failure from a TT0 iced probe event by observing the status page on the aircraft while the E1 (2) TT0 heater fail is active. If the status page indicates an engine short dispatch message while the E1 (2) TT0 heater fail is displayed on the cas then it is very likely that the TT0 heater system has a hardware problem and the corresponding maintenance manual task should be performed. Note that the above applies if an engine short dispatch message is not latched beforehand. If the status page does not indicate an engine short dispatch message while the E1 (2) TT0 heater fail is displayed on the cas then the fadec detected a TT0 iced probe event and is accommodating the situation as designed. In both cases the pilot needs to follow the afm procedure; namely: afm-2656 - FAA - section 04 - emergency and abnormal procedures engine 1 (2) TT0 heater fail exit or avoid icing conditions. It appears that to have an ice buildup on the TT0 probe while the heater is fully functional is acceptable. The issue isn't pilot awareness of the cas message. The issue is that ice is building up on the probe while the heater is fully functional. (Please note the TT0 probe is used to feed air data to the fadec and also display OAT and sat figures to pfd 1 & pfd 2).this causes a few safety issues: possible FOD damage; engine failure or fire if a large enough chunk of ice is ingested by the engine after accumulating on the TT0 probe. Pfd 1 & 2 tat & sat are unreliable. Without a reliable sat indication how can a pilot be sure that he will not damage the wing boots by accidentally inflating them below the -40C limitation? If the sat falsely indicates -35C but the actual sat is -42; and he activates the de-ice boots and they are damaged the pilot is in icing conditions with no way of removing the ice from his airplane. This creates a second possibly deadly situation. The afm/QRH procedure to 'exit or avoid icing conditions' is much more complex than it sounds. If flying in a cold environment where it is snowing on the ground the only way to exit icing is to land immediately. Should a TT0 failure occur in such an environment the pilot will declare an emergency and land as soon as possible since there is no 'fix' for this issue; when can he safely fly again? Does he have to wait until icing conditions are no longer present on the route of flight; or on the ground? To summarize: with this ongoing issue is the aircraft really safe to fly in known icing conditions?

Related reports:

Google
 

Original NASA ASRS Text

Title: An Embraer Phenom 100 CAS alerted ENG 1 & 2 TT0 HTR FAIL in icing conditions. The pilot descended out of icing and reported that the CAS alert indicated actual ice accumulation with the heaters enabled.

Narrative: In flight at an INDICATED SAT of -56C the aircraft began accumulating a trace of rime ice (visually detected the ice on the dark grey wing boots). I was flying in IMC with air mass thunderstorms in the vicinity of the aircraft. The radar was functional and was being used to avoid thunderstorms. I was approximately 20 miles west of a north/south running group of non connected but adjacent storms. The wind was about 40 KTS out of the south. I was flying a heading of 180 paralleling the storms. I selected both Engine Anti Ice switches to ON due to AFM limitation of -40C minimum temp for wing/stab de-ice boot operation. A few minutes later I received an ENG 1 TT0 HTR FAIL and ENG 2 TT0 HTR FAIL amber CAS messages. I immediately requested a descent to FL350 and a minute or two later was cleared to FL350 by ATC.The QRH procedure for this is: Icing Conditions............................... EXIT/AVOIDI have received this message a few times flying this aircraft. I cycled the E 1 & 2 anti ice OFF and back ON a few times but the message would always return. I was able to exit and avoid icing conditions around 30;000 FT. I continued the descent and landed uneventfully. The OAT was 25C on the ground.This is an ongoing issue with the Embraer Phenom 100. I reviewed a Central Maintenance Computer (CMC) download file indicting the TT0 probe had iced. The analysis showed that the TT0 probes installed on the inlet of the engines suffered from an ice build up during flight that impacted the TT0 measurement. The FADEC software has a new logic that prevents the adverse effects of this erroneous TT0 measurement on the engine thrust by turning OFF the TT0 Heater. This situation is currently annunciated to the pilot via the E1 (2) TT0 HEATER FAIL CAS message although the TT0 Heater itself is not failed. The pilot can distinguish a TT0 Heater hardware failure from a TT0 Iced probe event by observing the Status Page on the aircraft while the E1 (2) TT0 HEATER FAIL is active. If the status page indicates an ENG SHORT DISPATCH message while the E1 (2) TT0 HEATER FAIL is displayed on the CAS then it is very likely that the TT0 Heater system has a hardware problem and the corresponding Maintenance Manual task should be performed. Note that the above applies if an ENG SHORT DISPATCH message is not latched beforehand. If the status page DOES NOT indicate an ENG SHORT DISPATCH message while the E1 (2) TT0 HEATER FAIL is displayed on the CAS then the FADEC detected a TT0 Iced Probe event and is accommodating the situation as designed. In both cases the pilot needs to follow the AFM procedure; namely: AFM-2656 - FAA - SECTION 04 - EMERGENCY AND ABNORMAL PROCEDURES ENGINE 1 (2) TT0 HEATER FAIL Exit or avoid icing conditions. It appears that to have an ice buildup on the TT0 probe while the heater IS FULLY FUNCTIONAL is acceptable. The issue isn't pilot awareness of the CAS message. The issue is that ice is building up on the probe while the heater is fully functional. (Please note the TT0 probe is used to feed air data to the FADEC and also display OAT and SAT figures to PFD 1 & PFD 2).This causes a few safety issues: Possible FOD damage; engine failure or fire if a large enough chunk of ice is ingested by the engine after accumulating on the TT0 Probe. PFD 1 & 2 TAT & SAT are unreliable. Without a reliable SAT indication how can a pilot be sure that he will not damage the wing boots by accidentally inflating them below the -40C limitation? If the SAT falsely indicates -35C but the actual SAT is -42; and he activates the de-ice boots and they are damaged the pilot is in icing conditions with no way of removing the ice from his airplane. This creates a second possibly deadly situation. The AFM/QRH procedure to 'Exit or avoid icing conditions' is much more complex than it sounds. If flying in a cold environment where it is snowing on the ground the only way to exit icing is to land immediately. Should a TT0 failure occur in such an environment the pilot will declare an emergency and land as soon as possible since there is no 'fix' for this issue; when can he safely fly again? Does he have to wait until icing conditions are no longer present on the route of flight; or on the ground? To summarize: With this ongoing issue is the aircraft really safe to fly in known icing conditions?

Data retrieved from NASA's ASRS site as of July 2013 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.