# NTSB MIA93LA148: Piper PA-12, N4106M, Tampa, FL, July 2, 1993 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 2, 1993, 08:07 local (12:07 UTC) - Place: Tampa, FL - Coordinates: 28.049457, -82.44915 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=28.0495&lon=-82.4492&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report July 25, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 37366 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA93LA148 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/37366/pdf - Page: https://openairdocs.org/ntsb/MIA93LA148 ## Probable cause the improper welding/repair by maintenence personnel of the exhaust system, which eventually failed allowing hot exhaust gasses and flame to burn a fuel line and start a fire. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Fire, cruise - exhaust system,muffler - failure,partial (contributing factor) - maintenance,service of aircraft/equipment - improper, other maintenance personnel (cause) - exhaust system,muffler - fatigue (contributing factor) - Loss of engine power, cruise - Forced landing, descent - emergency - Fire, landing - roll ## Analysis WHILE TOWING A BANNER THE PILOT NOTED THE ENGINE FAILED AND A FIRE WAS OBSERVED FROM THE COWLING. HE RELEASED THE BANNER, EXECUTED A FORCED LANDING, AND EXITED THE AIRPLANE WITHOUT INJURY. THE AIRPLANE WAS DESTROYED BY FIRE. EXAMINATION OF THE MUFFLER SYSTEM REVEALED INTERGRANULAR AND FATIGUE CRACKING OF THE INLET PIPE SEAM. THIS ALLOWED HOT EXHAUST GASSES AND FLAME TO IMPINGE OF A FUEL LINE IN THE AREA STARTING A FIRE. ## Factual narrative On July 2, 1993, about 0807 eastern daylight dime, N4106M, a Piper PA-12, registered to and operated by Aerial Billboard Corporation, experienced an in-flight fire over Tampa, Florida, while on a 14 CFR Part 91 banner towing flight. Visual meteorological conditions prevailed at the time and no flight plan was filed for the local flight. The pilot was not injured and the airplane was destroyed by the fire. The flight originated from St. Petersburg, Florida, about 30 minutes earlier. The pilot stated the engine began to run rough, lose power and he observed flames from the cowling. He released the banner he was towing and executed a forced landing to an open field. He exited the airplane without injury and the airplane was destroyed by fire. The engine exhaust system and muffler were removed and forwarded to the NTSB laboratory for examination. Cracking of the inlet pipe sleeve on the heat exchanger was found with evidence that the crack had previously been repaired. The cracking exhibited signatures consistent with long term, progressive, intergranular degradation. The cracking progressed to about 1/3 of the seam and shifted from intergranular cracking to fatigue cracking at the end. This crack allowed the exhaust heat and flames to escape prematurely and impinge upon the fuel line in the area, initiating combustion and fire. ## Aircraft - Registration: [N4106M](https://openairdocs.org/deregistered/N4106M-2013-04-17), registration cancelled 2013-04-17, S/N 12-3002, built 1947 (OpenAirDocs) - Reported make and model: PIPER PA-12 - Registry model: [Piper PA-12](https://openairdocs.org/model/piper-pa-12) (registry code 7101202) (OpenAirDocs) - Registry engine: [Lycoming 0-235 series](https://openairdocs.org/engine/lycoming-0-235-series) (registry code 41505, 4 cycle) (OpenAirDocs) - Category: Airplane - Serial number: 3002 - Engines: LYCOMING O-235C 150 horsepower reciprocating - Damage: Destroyed - Fire: In-Flight - Flight: Other work use, Part 91 - Operator: Aerial Billboard Corp. - Registered owner: Aerial Billboard Corp - Airworthiness certificate: Standard, Utility; Standard, Normal - Last inspection: Annual, March 2, 1993 ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 26; commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: front; flight hours: 834 total, 41 in this make and model, 758 as pilot in command, 140 in the last 90 days, 42 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 7 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 70 °F - Altimeter: 30.00 inHg - Observed at: TPA, 11 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 (OpenAirDocs). - [Accident 19930702022299A](https://openairdocs.org/incident/19930702022299A), Jul 2, 1993: Piper PA12, Tampa, FL, Destroyed. Engine fire on banner tow. Dropped banner. Force landed. Prior. Welded mullfer cracked. Exaust ruptured fuel line. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.