Date: 201210
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: J3 Cub
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Landing
ATC / advisory: CTAF ZZZ
Reporter organization: Personal
Reporter function: Instructor; Pilot Not Flying
Reporter qualification: Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Troubleshooting; Workload; Training / Qualification
Second reporter function: Trainee; Pilot Flying
Anomaly: Ground Event / Encounter Ground Strike - Aircraft; Ground Excursion Runway; Inflight Event / Encounter Loss Of Aircraft Control
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Took Evasive Action; General Police / Security Involved
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

Narrative: The flight was an instructional flight in a Piper J3 Cub. I was the flight instructor; flying from the front seat. An ATP rated pilot was the student for tailwheel training; flying from the rear seat. We had been flying for about an hour; initially with air work including constant airspeed climbs and descents; power off stalls; and slow flight. We then did two landings and take offs from a small grass field several miles from our home airport. The day was clear and beautiful; with very light winds; essentially calm; when present from the southeast. We returned to our airport for our final planned landing; making a mid-field cross wind entry overhead to the right downwind for landing on Runway XX.The student was flying. He had done well with his earlier landings and I felt comfortable having him make this landing also. I had briefed him that a pavement landing was more challenging than grass and required even more precise directional control because of the pavement. We had previously discussed the center of mass location relative to main gear; and how that causes a ground loop tendency in tailwheel aircraft if the aircraft is not aligned with the direction of travel or is drifting at the time of touchdown. The approach and final approach segment were flown precisely on speed and on glide path. As we neared touchdown and were into the landing flare I noticed that the airplane began drifting very slightly to the right. It was my impression that the degree of drift and the alignment of the aircraft for landing were within safe bounds and therefore continued to monitor the landing letting the student maintain full control. After we touched down; just at stall with the stick full aft; the aircraft began to turn gradually left. I began to assist the student on the flight controls and then said 'I have it' as the rate of turn increased. Despite full right rudder and brake the turn developed into a progressive swerve to the left. I do not recall if I added left aileron. I noticed a small amount of power still on and I took this out. We left the runway between runway lights and continued to roll to the left on the grass. The radius of the turn tightened. There was no tendency of the airplane to tilt toward the outboard wing. At this time I began to see the PAPI lights to our left which were unfortunately the only obstructions except for a windsock on the left where otherwise there was a grassy field adjacent to the runway. As the turn continued we went past the first three lights and slowed; but the radius of the turn tightened despite all control inputs. We were slowing but still moving when we struck the fourth PAPI light with the right propeller blade. The engine and airplane came immediately to a stop. We were moving so slowly at the time of impact that there was no discernible force felt by us as occupants. There was no other damage to the aircraft. I shut off the magnetos; unfastened my belts and got out of the airplane to inspect the damage. I saw some oil dripping from the right rear valve cover and asked the other pilot to pull off the fuel valve. He also shut down our battery powered radio. We inspected the airplane and could see no damage except to the propeller (and of course possibly to the engine). I checked the brakes; bungees; and tailwheel. All seemed to be intact and functional. I initially wondered if there could have been a mechanical problem because the degree of side movement seemed to be in acceptable range at touchdown and I was caught by surprise by the ground loop. We did subsequently note that the airplane did not respond at all to rudder movement while pushing the airplane on the ground back to the hangar despite an engaged tailwheel and intact springs and linkages which were somewhat loose. Perhaps these should have been tighter. I have made thousands of tailwheel landings and felt that we were in comfortable control right up to the point that it became clear that the swerve was increasing and wewere going to depart the runway. I have to conclude this was mostly pilot error of not fully recognizing that lateral limits had been exceeded; perhaps exacerbated by a somewhat loose tailwheel steering linkage. After we got the airplane safety secured I was uncertain the proper way to report the event. I reviewed NTSB 830 on line and felt that by the clear definitions this event would not require reporting; however because we had damaged a PAPI light there seemed to be clearly a need to report this in a proper way. I called the Airport Manager and asked his advice. He requested that I have the Airport Desk report the event to the airport safety team. The other pilot in the airplane is very experienced and knows many of the FAA and airport officials in our area. He called a friend who is the head of the airport safety team and I talked with this person. We agreed the best thing was to report this to the FAA because of the PAPI damage. I wanted to be sure that the PAPI was inspected and NOTAMed out of service if necessary; before nightfall. So I also called the telephone number for the Local FSDO but the recording said that the office was closed. The recording gave a number to notify the Regional Office of an aircraft accident; but this seemed inappropriate. We called the Safety Officer back and he assured us that a NOTAM had already been filed so I felt better about that. We tried to reach an FAA friend of the other pilot; but reached only his voicemail. I called my former flight instructor for my CFI and he agreed that we had done all that we should at this point to notify appropriate authorities regarding what had happened; and that notifying the NTSB was not required. I decided to file this form; primarily as a way of leaving a document trail that explains our efforts to report this in the proper way and to follow reporting instructions thoughtfully and fully. This is an interesting dilemma regarding reporting: an event that seems clearly not to require reporting to either the NTSB or FAA on its own merits; but because it involves damage to a PAPI light it seems to me had to be brought to official attention.


Second narrative: I am acquainted with the Airport Operations Manager; so I contacted him at home and briefed him. He assured me that their people would take care of posting a NOTAM about the PAPI lights and would contact the FAA Tech Ops. I also called a FSDO Inspector at home that I am acquainted with and he volunteered to contact the FSDO person that we could report this incident to and have him contact us. This FAA person called both me and the instructor and took our information over the phone. Prior to our leaving the airport a member of the Airport Police Department from a nearby airport arrived and viewed the scene of the incident; the PAPI light; the airplane and took a statement from the instructor.It is my feeling that we went beyond required reporting; but because of the damage to the FAA PAPI light system we wanted to be very comfortable that all concerned parties were notified. This report is being filed to provide a consolidated summary of the events.


Synopsis: A J3 ATP rated pilot under instruction with an instructor lost control of the aircraft; ran off the runway and gently struck and broke a PAPI light which caused propeller damage.