N619AE

HISTORY OF FLIGHTOn November 11, 2019, about 0742 central standard time, American Eagle flight 4125, operated by Envoy Air, an Embraer EMB-145, N169AE, departed the left side of runway 10L while landing at Chicago O'Hare International Airport (ORD), Chicago, Illinois, and the right main landing gear collapsed. None of the 41 crewmembers and passengers aboard the airplane were injured, and the airplane sustained substantial damage. The flight was operating under Title 14 Code of Federal Regulations Part 121 as a domestic passenger flight that originated from Piedmont Triad International Airport (GSO), Greensboro, North Carolina.

The captain stated that, while at the gate at GSO, he and the first officer reviewed the expected weather conditions for ORD. The flight departed about 0522 (0622 local time). The captain was the pilot flying, and the first officer was the pilot monitoring. While enroute, the flight crew monitored the weather at ORD; the reported visibility was between 3/4 and 1 mile.

The Chicago approach controller initially assigned the flight to runway 9L. While the airplane was on the downwind leg of the approach, the controller changed the landing runway to 10L because runway 9L was closed for snow removal.

When the airplane was on short final approach to runway 10L, the tower controller instructed the flight to go-around. According to the cockpit voice recorder (CVR), the flight crew did not know the reason for the go-around. After conducting the go-around. the flight crew contacted the flight dispatcher and discussed various options, including diverting to the alternate airport (Cincinnati/Northern Kentucky International Airport, Hebron, Kentucky) or changing the alternate airport to one that was closer to the airplane’s position at the time. The crew elected to make another approach to ORD. The Chicago approach controller provided vectors for the approach to runway 10L. The airplane intercepted the localizer and glideslope for the runway.

According to the CVR transcript, at 0739:34, the first officer notified the tower controller that the flight had arrived at the final approach fix. About 2 seconds later, the tower controller stated that the “RCC [runway condition code] is 555 – braking medium to poor up to [taxiway] November 3 and poor past [that point].” The first officer acknowledged this information. (A runway condition code of 5/5/5 indicated good braking action on each one-third of the runway, as discussed in the Airport Information and Additional Information sections of this report. Taxiway N3 was about halfway down the runway.)

At 0740:28, the controller cleared the flight to land and stated that the wind was from 360° at 17 knots with gusts to 24 knots. The first officer acknowledged the clearance. After the accident, the flight crewmembers reported that the approach was stable, and that the airplane broke out of the clouds when it was about 500 ft above ground level. According to flight data recorder (FDR) data, the autopilot was disengaged at 0741:30, but vertical and lateral guidance remained on the flight director until touchdown.

At 0741:32, the first officer called, “runway in sight,” and the captain stated, “roger – landing.” At 0741:59, the CVR recorded a sound similar to the landing gear touching down, and the FDR showed that the inboard and outboard wheel brake pressure began to increase about 1 second later. At 0742:02, the thrust reversers were deployed, and the airplane’s groundspeed was 127 knots. About that time, the first officer stated, “stay on that centerline,” and the captain stated “yep” followed by expletives. At 0742:08 and 0742:12, the CVR recorded sounds similar to the airplane slowing down and sounds similar to reverse thrust increasing, respectively. At 0742:15 the airplane began to turn to the left with the thrust reverser levers still deployed.

At 0742:22, the CVR recorded sounds similar to the thrust reverse levers being moved to forward idle. As the reversers were stowed, the inboard and outboard wheel brake pressures increased, and the airplane continued to turn to the left. FDR data showed that, when the thrust reversers were stowed, the airplane’s groundspeed was 39 knots. Afterward, the captain stated an expletive and “ugh,” and the CVR recorded an increase in background noise. At 0742:29, the airplane’s vertical acceleration was 1.64 G, and its lateral acceleration was -0.85 G. About 1 second later, the CVR recorded the master warning “landing gear,” which continued until the end of the recording (at 0805:51).

After the accident, the captain reported that the airplane touched down on the runway centerline and that, as brakes were applied, the airplane moved off the centerline. The first officer reported that the airplane started swerving to the right when its indicated airspeed was about 80 knots. As the captain applied corrections to maneuver back to the centerline, the airplane started to slide to the left. The captain stated that he applied maximum reverse thrust and brakes but that the airplane continued to slide to the left at a speed of about 60 knots. The first officer stated that, at that time, the airplane “experienced an uncommanded swerve” toward taxiway N1, which was about one-third of the way down the runway from the approach end. FDR data shows that no more than +/- 3 degrees of rudder deflection was used.

The airplane subsequently slid off the end of the runway and onto the grass on the left side of the runway, as shown in figure 1. The right main gear collapsed when the airplane departed the runway surface and entered the grass area.

Figure 1. Airplane’s resting position after runway excursion (Source: Envoy Air).

At 0742:32, the controller asked the flight crew if assistance was needed, and the first officer replied, “need assistance.” After the accident, the captain reported that, because no fire was occurring, he determined that the passengers should remain aboard the airplane until emergency services and shuttle buses arrived. According to airport event logs, the Chicago Fire Department arrived on scene about 0747. No passengers requested medical assistance, and airport rescue and firefighting personnel helped to deplane the passengers and crew via the main cabin door and a rescue ramp. The first officer reported that the runway had snow and that the nearby taxiway was “very icy.” The shuttle buses arrived at the assigned airport gate about 1 hour after the accident.

After the accident, the captain stated that he did not recall hearing any braking reports other than 5/5/5, and the first officer recalled that the controller reported “good” braking action before taxiway N3 and “3” (medium) past taxiway N3. Both pilots stated that, according to company guidance, the runway condition codes are “controlling” and that pilot reports are advisory. METEOROLOGICAL INFORMATIONORD had an automated surface observing system (ASOS) that was augmented by certified weather observers. A review of the ASOS observations indicated that, on the day before the accident (November 10, 2019), precipitation started as light rain at 2036 and changed over to light snow at 2351 with temperatures falling to -6.1°C (21°F). Snow ended at 1735 on the day of the accident (November 11); a total of 3 inches of snow was reported.

At 0551 on November 11, the ASOS reported 2 inches of snow on the ground with light snow continuing through the time of the accident. Low instrument flight rules conditions and a visibility under 1 statute mile prevailed at the time of the accident.

The ASOS 5-minute observation for 0740 resulted in a crosswind of 18 to 28 knots and a 3- to 5knot tailwind component for landing on runway 10L. The ASOS also made 1-minute observations, which included the 2-minute average wind and the 5-second maximum wind. The 2-minute average wind at 0743 indicated that the crosswind component for landing on runway 10L was 15 knots with a 4-knot tailwind. The 5-second maximum wind showed a crosswind of 23 knots with a 6-knot tailwind.

Numerous pilot reports of light rime icing conditions in the ORD area were received during the time surrounding the accident. Pilot reports of braking action before the accident ranged from medium to poor, as further discussed in the Airport Information section. WRECKAGE AND IMPACT INFORMATIONPost-accident aircraft examination found no anomalies with the nosewheel steering system or the spoiler system. The braking system was checked in accordance with the Aircraft Maintenance Manual with no faults found. None of the tires showed any signs of rubber reversion, flat spotting, or abnormal wear. The rudder system and thrust reversers passed their respective operational tests with no faults found.

The nosewheel steering manifold assembly was functionally tested, and it was observed that during test setup, with hydraulic pressure applied but no electrical command input to the unit, the C2 output port pressure increased while the C1 output port pressure remained near 0 psi. While this behavior was unexpected by the manufacturer, when electrical command input was supplied to the nosewheel steering manifold assembly (as it would have been during the accident), the unit performed as expected. The electrohydraulic servo valve, which is a subcomponent of the nosewheel steering manifold assembly, was removed for additional testing. A new electrohydraulic servo valve was placed in the nosewheel steering manifold assembly for functional testing, and the assembly passed all performed tests.

Functional testing of the electrohydraulic servo valve was performed according to the manufacturer’s acceptance test procedure, and the unit met the as-new acceptance test limits for all performed tests except for a slight exceedance observed during the flow gain test. According to the manufacturer, this flow gain exceedance could result in a small increase in the speed of the nosewheel deflection in the commanded direct...