- Date
- October 7, 1993, 19:40 local (23:40 UTC)
- Place
- San Juan, PR
- Injuries
- 2 uninjured
- Damage
- Substantial damage
- Phase of flight
- Landing
- Aircraft
- N781TDouglas DC-3C
- Weather
- Visual (VMC) · Dusk
- Status
- Completed · report September 13, 1994
- Report
- Approved by Office Director
- FAA report
- 19931007052509A
- Case key
- 37445
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
Partial failure of a wing rib due to exfoliation corrosion and inadequate inspection of the aircraft by company maintenance personnel.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
After an uneventful landing while taxiing, the captain noticed that a section of the left wing was bent up. Examination of the airplane revealed that rib no. 19 in the left wing failed chordwise midpoint between a row of rivets and nutplates on the lower attach angle due to exfoliation corrosion. The FAA approved 50-hour inspection requires visual inspection of the attach angle and bolts but does not require removal of the wing tip.
Factual narrative
On October 7, 1993, about 1940, Atlantic standard time, a Douglas DC-3C, N781T, registered to and operated by Tol Air Services, Inc., under 14 CFR Part 135, flight No. 522, as a nonscheduled, international, cargo flight, was substantially damaged on landing at the Luis Munoz Marin International Airport, San Juan, Puerto Rico. Visual meteorological conditions prevailed at the time and an IFR flight plan was filed for the flight from Santiago, Dominican Republic. The airline transport-rated captain and commercial-rated copilot were not injured. The flight originated about 2 hours 2 minutes earlier.
The pilot-in-command stated that the second pilot had landed the airplane and while taxiing, he observed that an outer section of the left wing was bent up.
Examination of the airplane revealed that Rib No. 19 of the left wing failed. The failed rib was removed and sent to Douglas Aircraft Company for analysis.
Analysis of the rib revealed that it failed chordwise due to exfoliation corrosion midpoint between the rivet line and the nutplate line on the lower horizontal section. According to McDonnell Douglas personnel, the location of the corrosion could not be observed by a flightcrew when performing a walk around inspection but can be observed during the FAA approved 50-hour inspection.
Review of the FAA approved 50-hour inspection checklist used for the inspection specifically states to inspect all interior structures for corrosion, damage condition and security. Additionally, the outer wing attach angles and bolts are required to be inspected.
Aircraft
- Registration
- N781T
- Reported as
- Douglas DC-3C
- Category
- Airplane
- Serial number
- 4306
- Airframe hours
- 36,964
- Engine
- P&W R1830-92, 1,200 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Part 135
- Registered owner
- Tol Air Services, Inc.
- Airworthiness certificate
- Standard, Transport
- Last inspection
- AAIP · September 4, 1993 · 39 hours before
- Departed
- MDST · Santiago, OF
- Flight plan
- IFR
- Airport
- SJU · Luis Munoz Marin Int'L, runway 10, 8,016 × 150 ft, concrete
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 30
- Certificates
- Commercial, Airline transport, Private
- Airplane ratings
- Single-engine sea, Single-engine land, Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Class 1, Valid Medical--no waivers/lim.
- Seat
- Left
- Flight hours
- 2,450 total · 669 in this make and model · 1,715 as pilot in command · 164 in the last 90 days · 58 in the last 30 days · 1 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Dusk
- Wind
- 90° at 6 knots
- Visibility
- 13 statute miles
- Lowest ceiling
- 28,000 ft overcast
- Temperature
- 81 °F, dew point 73 °F
- Altimeter
- 29.00 inHg
- Observed at
- SJU, 1 nm away
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.