Accident de Havilland DH.112 Venom FB54 N747J,
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ASN Wikibase Occurrence # 213548
 
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Date:Friday 20 July 2018
Time:16:04
Type:Silhouette image of generic VNOM model; specific model in this crash may look slightly different    
de Havilland DH.112 Venom FB54
Owner/operator:World Heritage Air Museum
Registration: N747J
MSN: J1747
Year of manufacture:1957
Engine model:De Havilland Ghost
Fatalities:Fatalities: 1 / Occupants: 1
Aircraft damage: Destroyed
Category:Accident
Location:SW of Sheboygan County Memorial Airport, WI -   United States of America
Phase: Take off
Nature:Private
Departure airport:Sheboygan Memorial Airport, WI (SBM/KSBM)
Destination airport:Sheboygan Memorial Airport, WI (SBM/KSBM)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot was conducting a formation training flight consisting of two airplanes; the accident airplane was in the No. 2 position. The airplane took off about 8 seconds behind the lead (No. 1 position) airplane. Witnesses described the airplane's takeoff as sluggish and indicated that the airplane's wings rocked back and forth shortly after lifting off. The witnesses' testimony was consistent with one witness' video recording, which showed the airplane climbing away from the runway and making a shallow left turn. As the airplane passed the witness' position, the engine sound decreased and rapidly increased. The airplane reached an altitude of about 200 ft above the ground before descending and impacting a farm structure. Another video captured the airplane descending in a slightly nose-up and wings-level attitude before impact. The flaps and landing gear both appeared retracted in that video.

No preimpact anomalies with the airframe and engine were found that would have precluded normal operation of the airplane. Signatures consistent with circumferential rub marks within the turbine were identified. Although the rate of rotation at the time of impact could not be determined, the retraction of the landing gear at a normal rate showed that the engine was likely producing some power at that time.

One of the witnesses to the accident was a pilot with experience in the accident make and model. He described the engine powering the airplane as "high airflow and thrust" and indicated that the engine could experience a compressor stall when operating at a high angle of attack and a high-power setting. He also stated that the airplane could get into a low energy state if an engine failure occurred and that the airplane would normally accelerate "very quickly" if it leveled off at 200 ft.

The witness accounts of the accident airplane's wings rocking back and forth were consistent with the airplane encountering the wake turbulence of the lead airplane. Wake turbulence can disrupt airflow to the engine of a trailing airplane. The final seconds of the witness' video showed the pilot controlling the airplane during the climb to 200 ft, after which the airplane began descending. Thus, the wake turbulence from the lead airplane likely disrupted airflow to the engine and caused a compressor stall and a partial loss of engine power, which resulted in the airplane's inability to continue to climb.

Toxicology testing identified sedating medications in the pilot's specimens, but the levels of the medications at the time of the crash were well below the levels that would have caused significant effects. Therefore, it is unlikely that impairing effects of these medications contributed to this accident.

Probable Cause: The airplane's encounter with wake turbulence from the lead airplane in the formation flight, which resulted in a compressor stall and the airplane's subsequent inability to climb.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: WPR18FA200
Status: Investigation completed
Duration: 2 years 1 month
Download report: Final report

Sources:

NTSB
FAA register: http://www.warbirdregistry.org/jetregistry/venomregistry/venom-j1747.html
https://flightaware.com/photos/view/168017-bd5af4ed918ed46f10b8fa4a94cb738d67fc7b51/aircrafttype/VENM

Location

Media:

Revision history:

Date/timeContributorUpdates
20-Jul-2018 22:40 Geno Added
20-Jul-2018 23:48 Geno Updated [Time, Aircraft type, Total fatalities, Total occupants, Other fatalities, Phase, Departure airport, Source, Narrative, Plane category]
21-Jul-2018 07:25 ANON Updated [Aircraft type, Source]
21-Jul-2018 07:32 angels one five Updated [Aircraft type, Registration, Source]
21-Jul-2018 07:33 harro Updated [Aircraft type, Operator]
21-Jul-2018 07:36 harro Updated [Cn, Departure airport, Source]
21-Jul-2018 07:42 Iceman 29 Updated [Time, Source, Embed code]
21-Jul-2018 10:14 Iceman 29 Updated [Source, Embed code]
21-Jul-2018 10:20 Iceman 29 Updated [Nature, Narrative]
21-Jul-2018 10:21 Iceman 29 Updated [Source, Narrative]
21-Jul-2018 17:11 Aerossurance Updated [Location, Departure airport, Source, Narrative]
21-Jul-2018 19:48 A.J. Scholten Updated [Source]
21-Jul-2018 20:49 Geno Updated [Source]
31-Jul-2018 16:43 Iceman 29 Updated [Source, Narrative]
22-Jul-2020 06:34 aaronwk Updated [Departure airport, Source]
01-Sep-2020 16:55 ASN Update Bot Updated [Time, Cn, Nature, Departure airport, Destination airport, Source, Embed code, Narrative, Accident report, ]
01-Sep-2020 19:16 harro Updated [Departure airport, Destination airport, Source, Embed code, Narrative, Accident report, ]

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