Narrative:
Swift Air flight 3518, a Boeing 737-800, N820TJ, was climbing through about 8,000 feet when the flight crew heard a loud bang but the systems and engine indications remained normal. The flight crew elected to continue to San Diego International Airport (SAN), California. Post-flight examination of the airplane found that the vertical stabilizer dorsal fin and several other panels were missing. The left horizontal stabilizer was substantially damaged from impact with the missing components.
On February 26, 2019 (less than 3 months before the accident), the fuselage skin under the dorsal fin was inspected at iAero Repair Station, Miami, Florida. This inspection was done every 24,000 flight cycles to identify and remove corrosion. The maintenance instructions for the dorsal fin indicated that the mechanic should note the type and location of the bolts removed to ensure that each bolt would be returned to the same location from where it was removed. (The dorsal fin had different bolts with varying grip lengths.) Once the bolts were reinstalled, sealant was applied to the bolt heads.
Most of the dorsal fin, the vertical stabilizer panels, and 7 of the 14 bolts attaching the dorsal fin to the fuselage were not recovered. Of the seven bolts that were recovered, four remined installed, and three were found loose. Three of the four installed bolts remained attached to pieces of the dorsal fin structure. Examination of the photographs showed that the bolts installed in three positions on the left side of the dorsal fin were the correct part number. The bolt installed in a position on the right side of the dorsal fin was not the correct part number, and the bolt was longer than required. The photographs also showed remnants of old sealant at each of the bolt locations but no evidence that sealant was applied during maintenance of the dorsal fin in February 2019 (less than 3 months before the accident).
The seven missing bolts for the dorsal fin structure became loose, had fractured, or were not properly installed.
Probable Cause: Improper installation of dorsal fin attach bolts which caused the dorsal fin to separate during flight, substantially damaging the left horizontal stabilizer.
accident date: 19-05-2020
type: Boeing 737-8Q8 (WL)
registration: N820TJ
| Status: | Accident investigation report completed and information captured |
| Date: | Tuesday 19 May 2020 |
| Time: | 15:16 |
| Type: |  Boeing 737-8Q8 (WL) |
| Operator: | Swift Air |
| Registration: | N820TJ |
| MSN: | 28218/160 |
| First flight: | 1998-11-24 (21 years 6 months) |
| Engines: | 2 CFMI CFM56-7B26 |
| Crew: | Fatalities: 0 / Occupants: 7 |
| Passengers: | Fatalities: 0 / Occupants: 88 |
| Total: | Fatalities: 0 / Occupants: 95 |
| Aircraft damage: | Substantial |
| Aircraft fate: | Repaired |
| Location: | W of Victorville-Southern California Logistics Airport, CA (VCV) ( United States of America)
|
| Phase: | Initial climb (ICL) |
| Nature: | Domestic Scheduled Passenger |
| Departure airport: | Victorville-Southern California Logistics Airport, CA (VCV/KVCV), United States of America |
| San Diego International Airport, CA (SAN/KSAN), United States of America | |
| Flightnumber: | 3518 |
Swift Air flight 3518, a Boeing 737-800, N820TJ, was climbing through about 8,000 feet when the flight crew heard a loud bang but the systems and engine indications remained normal. The flight crew elected to continue to San Diego International Airport (SAN), California. Post-flight examination of the airplane found that the vertical stabilizer dorsal fin and several other panels were missing. The left horizontal stabilizer was substantially damaged from impact with the missing components.
On February 26, 2019 (less than 3 months before the accident), the fuselage skin under the dorsal fin was inspected at iAero Repair Station, Miami, Florida. This inspection was done every 24,000 flight cycles to identify and remove corrosion. The maintenance instructions for the dorsal fin indicated that the mechanic should note the type and location of the bolts removed to ensure that each bolt would be returned to the same location from where it was removed. (The dorsal fin had different bolts with varying grip lengths.) Once the bolts were reinstalled, sealant was applied to the bolt heads.
Most of the dorsal fin, the vertical stabilizer panels, and 7 of the 14 bolts attaching the dorsal fin to the fuselage were not recovered. Of the seven bolts that were recovered, four remined installed, and three were found loose. Three of the four installed bolts remained attached to pieces of the dorsal fin structure. Examination of the photographs showed that the bolts installed in three positions on the left side of the dorsal fin were the correct part number. The bolt installed in a position on the right side of the dorsal fin was not the correct part number, and the bolt was longer than required. The photographs also showed remnants of old sealant at each of the bolt locations but no evidence that sealant was applied during maintenance of the dorsal fin in February 2019 (less than 3 months before the accident).
The seven missing bolts for the dorsal fin structure became loose, had fractured, or were not properly installed.
Probable Cause:
Probable Cause: Improper installation of dorsal fin attach bolts which caused the dorsal fin to separate during flight, substantially damaging the left horizontal stabilizer.
Accident investigation:
|
Sources:
» NTSBPhotos
accident date: 19-05-2020
type: Boeing 737-8Q8 (WL)
registration: N820TJ
Video, social media
Yesterday I posted the photo on the left of N820TJ landing in San Diego with parts of its tail missing. I received the photo on the right along with information that the damage occurred in flight and the crew was unaware. @JustJettingThru was key in updating me.#avgeek pic.twitter.com/3NgE2yC5YQ
Doug Kempf (@dougkempf) May 21, 2020
Map
This map shows the airport of departure and the intended destination of the flight. The line is connecting ADS-B datapoints from Flightradar24.
Distance from Victorville-Southern California Logistics Airport, CA to San Diego International Airport, CA as the crow flies is 207 km (129 miles).
Accident location: Approximate; accuracy within a few kilometers.
Distance from Victorville-Southern California Logistics Airport, CA to San Diego International Airport, CA as the crow flies is 207 km (129 miles).
Accident location: Approximate; accuracy within a few kilometers.
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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