Sikorsky S-58JT accident near Middletown, Delaware, August 1, 2012
On August 1, 2012 at about 1:00 pm local time, a 1959 Sikorsky S-58JT (helicopter), registered N126GW, was substantially damaged in an accident near Middletown, Delaware (Parking Lot airport). It was an external-load flight under external-load helicopter rules (Part 133). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
The pilot's failure to recognize that the helicopter was experiencing tail rotor dynamic instability and to take immediate corrective actions during an external load lift, which resulted in the failure of a tail rotor blade.
Source: NTSB aviation accident database, copy made September 29, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 1, 2012 · about 1:00 pm local time
- Place
- Middletown, Delaware · Parking Lot · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Sikorsky S-58JT, built 1959 · all S-58JTs on the register
- Registration
- N126GW · registry record · serial 581124
- Damage
- Substantial damage
- Flight
- External-load flight · external-load helicopter rules (Part 133)
The NTSB's narrative final · quoted from the NTSB record
The pilot had flown two uneventful external load lifts to place 2,900-lb air conditioning units on a warehouse roof. The pilot reported that, during the third lift, he felt vibration in the pedals that became violent, and the helicopter then began to rotate about its vertical axis. The air conditioning unit touched down on the roof as the helicopter was spinning. The pilot could not stop the helicopter's rotation, so he released the cable attached to the air conditioning unit and then maneuvered the helicopter away from the warehouse. He then increased forward speed, turned right to line up with a street, and conducted a roll-on landing. Examination of the helicopter revealed that the entire aft portion of one of the four tail rotor blades had separated just aft of the blade's spar where a bond line existed. Examination of the tail rotor blade revealed high-stress progressive crack growth features at the root end of the fracture, buckling deformation adjacent to the fracture, and bending deformation of the leading edge, all of which were consistent with the tail rotor blade fracturing due to dynamic instability in the tail rotor. The progressive crack growth features observed on the fracture surface were associated with relatively high stress and few cycles and likely occurred after the deformation associated with the buckling. In addition, all four tail rotor blades exhibited bending deformation, indicating that they all experienced loads that exceeded the allowable design loads, and the deformation pattern was consistent with an external input on the tail rotor assembly overloading all of the blades rather than a failure in the blade causing it to become unstable. The helicopter manufacturer confirmed that such damage can be caused by dynamic tail rotor instability and that such instability can be accompanied by tail rotor vibration, as was experienced during the accident flight. Although dynamic tail rotor instability rarely occurs, it has been known to occur on the accident helicopter make and model. To improve tail rotor stability, the helicopter manufacturer had introduced two modifications to the tail rotor system, and both of these modifications had been installed on the accident helicopter. Even with the modifications, dynamic tail instability can occur, and high values of left pedal, improper tail rotor cable tension (too high or too low), bottoming of the tail rotor control system spring, higher rotor speed, or relative wind from the right
The NTSB's narratives can run to many pages; this is the opening. Read the full report at the NTSB.
About this page
Everything above comes from the NTSB's public accident database and is rewritten in plain English only where the NTSB used codes; the probable cause and narrative are the NTSB's own words. This site never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number ERA12LA493.