FlarePath

What happened

NTSB summary, verbatim

The airplane received minor damage when it sustained a lightning strike while on approach. The flightcrew subsequently encountered elevator control binding, although they were able to land without further incident. Both flightcrew members indicated that the control yoke could be manipulated in the aft direction, but that it would not move forward past about 60-percent deflection. A postaccident inspection of the airplane revealed that the tailcone was damaged. Examination of the damage disclosed that the tailcone's light assembly wiring harness and its respective overbraid shielding were thermally damaged. A bulkhead frame was dislodged from its location due to the thermal damage present on the wiring harness. The dislodged bulkhead came to rest on the elevator's bellcrank, which restricted the flightcrew's ability to control the elevator. Subsequent to the incident, the airplane's manufacturer redesigned the tailcone. The new design incorporates a light assembly secured to the tip of the tailcone by an aluminum retaining strap. In this design four diverters are installed on the exterior tailcone skin which are electrically bonded to the metallic retaining strap of the light assembly and to the metallic bonding plate installed in each side of the fairing.

Photographs

21the aircraft, and what the investigators found

The aircraft before the accident

Wreckage and site documentation · 20 photographs from the docket

Photographs are NTSB docket attachments — works of the US government, in the public domain. Captions are the Board’s own.

Probable cause

the Board's determination

An in-flight encounter with lightning. Contributing to the incident was the damaged and displaced tailcone bulkhead frame that inhibited the full travel of the elevator during approach.

Occurrence sequence

2 stepsNTSB coding · CICTT taxonomy

1 · Approach-IFR final approach
Other weather encounter
2 · Approach-IFR final approach
Flight control sys malf/fail
defining event

Findings

2 causal · 1 contributing

CAUSE
Environmental issues › Conditions/weather/phenomena › Convective weather › Lightning — Effect on equipment
CAUSE
Aircraft › Aircraft systems › Flight control system › Elevator control system — Damaged/degraded
FACTOR
Aircraft › Aircraft systems › Flight control system › Elevator control system — Design

Sequence of events

2 timed eventsfrom the FDR factual report · claude-fable-5-1 (in-session)

approach from 10,000 ft (plot 1)approachp.4
Approach via waypoints KAYTO, PINKK and MONKZ plotted with latitude/longitude, roll, heading, autopilot, pitch, pitch trim, both control columns, right elevator, airspeed, altitude and radio altitudes
shortly after PINKKapproachp.4
Autopilot disconnected (crew reported this as the moment of the lightning strike); no obvious control binding - control column and right elevator movements correlate well; no other bus, display or warning discrete changed state at that time

NTSB analysis

from the final report

The airplane received minor damage when it sustained a lightning strike while on approach. The flightcrew subsequently encountered elevator control binding, although they were able to land without further incident. Both flightcrew members indicated that the control yoke could be manipulated in the aft direction, but that it would not move forward past about 60-percent deflection. A postaccident inspection of the airplane revealed that the tailcone was damaged. Examination of the damage disclosed that the tailcone's light assembly wiring harness and its respective overbraid shielding were thermally damaged. A bulkhead frame was dislodged from its location due to the thermal damage present on the wiring harness. The dislodged bulkhead came to rest on the elevator's bellcrank, which restricted the flightcrew's ability to control the elevator. Subsequent to the incident, the airplane's manufacturer redesigned the tailcone. The new design incorporates a light assembly secured to the tip of the tailcone by an aluminum retaining strap. In this design four diverters are installed on the exterior tailcone skin which are electrically bonded to the metallic retaining strap of the light assembly and to the metallic bonding plate installed in each side of the fairing.

EMBRAER EMB-145LREXPRESSJET AIRLINES INC