MD-11
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
General Maintenance Action
Aircraft
Received WSHLD HEAT L FAIL when placed all A/I (Anti-Icing) on before entering crosswind. On the arrival descending to FL200 in heavy rain and moderate or greater turbulence; ATS OFF illuminated and ATC requested right orbit at present position for spacing. Shortly thereafter received IAS on both PFDs (Primary Flight Display); AP (Autopilot) OFF; then SEL ELEV FEEL MAN; and SEL FLAP LMT OVRD. Lost both flight directors; and neither AP would remain engaged; with all malfunction indications coming on and going off intermittently.While attempting to maintain aircraft control and talk to arrival; experienced deviations to clearance. Radios were very congested due to multiple deviation requests. Advised ATC as soon as possible of flight systems malfunction and requested heading. Was about to request a block altitude for troubleshooting when ATC asked if we wanted priority handling which we accepted. We suspected icing was our issue; and this allowed us immediate descent to lower/warmer altitude while the FO (First Officer) ran checklists. The suspect systems remained intermittent remainder of flight which required a manually flown raw data ILS to an uneventful landing in heavy rain. All systems returned to normal by rollout.Severe weather; system malfunction; heavy radio frequency congestion. Hard to say because the multitude of weather related issues were difficult to predict; but the pitot static anti-ice systems appear to have not been sufficient for the conditions.
As we were operating into ZZZ the weather conditions in ZZZ were less than optimal. There were numerous thunderstorms around the area and numerous aircraft asking for weather avoidance. Approaching the terminal area we selected engine and airframe icing on as well as windshield heat before the descent. Almost immediately we received a WSHLD LEFT FAIL annunciation.As we continued our descent; at approximately FL230; the auto-throttles disconnected on their own. Soon thereafter we received a SEL ELEV FEEL MAN annunciation followed immediately by SEL FLAP LIM OVRD and the IAS COMPARITOR MONITOR. Within approximately a minute the autopilot disengaged and would not immediately re-engage.We were in and out of IMC conditions with moderate to occasionally severe turbulence at this point and that is when Approach asked us to do a right 360 degree turn. We were already picking our way around cells and with the degradation of our systems I told Approach we were having some system issues and requested a more direct heading. There was a ton of frequency congestion with other aircraft asking for weather deviations and the radio performance was poor due to the weather. Approach asked us if we would like priority handling to which I responded affirmative.While all the radio chatter was happening both flight directors decided to quit and we lost all flight guidance. We ran all appropriate checklists and all systems appeared to return to normal. We were able to re-engage the autopilot for a few minutes and then the cascade of failures happened again. I never noticed a disparity between the Captain's airspeed indicator; mine; or the standby. From altitude all the way to touchdown they all appeared to be giving good information. Received good vectors for an ILS which the Captain flew raw data with no automation in heavy rain to an uneventful landing. He did an exemplary job.
MD-11 flight crew reported Anti Icing systems failure resulting in loss of flight directors and Autopilot functionality during approach.