# NTSB LAX94LA377: Piper PA-32RT-300T, N39658, San Mateo, CA, September 25, 1994 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: September 25, 1994, 13:50 local (20:50 UTC) - Place: San Mateo, CA - Coordinates: 37.539291, -122.299652 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=37.5393&lon=-122.2997&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 2 serious - Status: Completed, report May 16, 1995 - Report: Approved by Office Director - NTSB case key (mKey): 28871 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX94LA377 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/28871/pdf - Page: https://openairdocs.org/ntsb/LAX94LA377 ## Probable cause A deteriorated magneto grounding ('P' lead) and failure of maintenance personnel to detect this condition when the engine was reinstalled in the airframe after overhaul. The lack of suitable terrain for the forced landing was a factor. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - nonmechanical, climb - to cruise - ignition system,magneto grounding lead (p-lead) - deteriorated (cause) - ignition system,magneto grounding lead (p-lead) - shorted (cause) - maintenance,inspection - inadequate, other maintenance personnel (cause) - Forced landing, emergency descent/landing - In flight collision with object, landing - flare/touchdown - terrain condition - residential area - terrain condition - none suitable (contributing factor) - object - wire,transmission - object - vehicle - object - wall/barricade ## Analysis THE AIRCRAFT LOST ENGINE POWER AFTER TAKEOFF AND WAS FORCED TO LAND ON A RESIDENTIAL STREET. THE ENGINE HAD BEEN OVERHAULED BY AN FAA-CERTIFIED REPAIR STATION 5 MONTHS AND 150 FLIGHT HOURS BEFORE THE ACCIDENT. EXAMINATION OF THE ENGINE MAGNETO REVEALED INTERNAL CORROSION AND ELECTRICAL ARCING AT THE BREAKER POINTS. THE INSULATION ON THE 'P' LEAD WIRE WAS CRACKED ALONG ITS ENTIRE LENGTH EXPOSING BARE WIRE AT ONE POINT. GROUNDING OF THE 'P' LEAD AS A RESULT OF A BARE WIRE TOUCHING THE AIRFRAME WOULD HAVE THE SAME EFFECT AS THE IGNITION SWITCH IN THE OFF POSITION. ## Factual narrative On September 25, 1994, at 1350 hours Pacific daylight time, a Piper PA-32RT-300T, N39658, lost engine power after takeoff and was forced to land on a residential street in San Mateo, California. The airplane was being operated by Aero Haven, Inc., Big Bear City, California, as a personal flight. The airplane was destroyed. The certificated private pilot and passenger received serious injuries. The flight originated from the San Carlos Airport, San Carlos, California, about 1345 hours and was destined for Big Bear City. Visual meteorological conditions prevailed. The pilot stated the engine quit abruptly 1,000 to 1,500 feet above the ground over a city. The pilot manipulated the throttle in order to regain power. After getting no response, he elected to land on a residential street. The airplane struck wires during the initial flare and then struck an automobile and finally a brick wall during the ground run. The airplane's maintenance records revealed the engine had been overhauled by a Federal Aviation Administration (FAA) certified repair station on May 5, 1994, about 150 flight hours before the accident. The repair station certified the airplane to be airworthy after the engine was reinstalled and returned the airplane to service. The airplane's engine was examined at the El Monte Airport, El Monte, California, on October 21, 1994. Examination of the magneto revealed internal corrosion and electrical arcing at the breaker points. The impulse coupling was found intact and functioned. The insulation on the "P" lead wire was cracked along its entire length exposing bare wire at one point. According to the engine manufacturer, the "P" lead wire connects the magneto's coil with the ignition switch. With the ignition switch in the off position, the "P" lead grounds the primary current. With the "P" lead grounded, the opening of the breaker points does not interrupt the primary current, preventing any build up of voltage in the primary circuit. Without primary voltage, the magneto will not fire the spark plugs. Grounding of the "P" lead as a result of a bare wire touching the airframe would have the same effect as the ignition switch in the off position. ## Aircraft - Registration: [N39658](https://openairdocs.org/deregistered/N39658-1997-07-15), registration cancelled 1997-07-15, S/N 32R7887135 (OpenAirDocs) - Reported make and model: PIPER PA-32RT-300T (PA-32RT-30) - Registry model: [Piper PA-32RT-300T](https://openairdocs.org/model/piper-pa-32rt-300t) (registry code 7103216) (OpenAirDocs) - Category: Airplane - Serial number: 32R-7887135 - Airframe hours: 1429 - Engines: LYCOMING TIO-540-S1AD 300 horsepower reciprocating - Damage: Destroyed - Flight: Personal, Part 91 - Operator: Aero Haven, Inc. - Registered owner: Regli, Mike L. - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, August 29, 1994, 15 hours before - Departed: SQL, SAN CARLOS, CA - Destination: L35, BIG BEAR CITY, CA - Airport: SQL, San Carlos ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 34; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; seat: left; toxicology performed; flight hours: 340 total, 45 in this make and model, 330 as pilot in command, 45 in the last 90 days, 35 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 20° at 8 knots - Visibility: 8 statute miles - Lowest ceiling: none - Temperature: 70 °F, dew point 61 °F - Altimeter: 29.00 inHg - Observed at: SQL, 4 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 19940925030609A](https://openairdocs.org/incident/19940925030609A), Sep 25, 1994: Piper PA32RT300T, San Carlos, CA, Destroyed. Lost power on initial climbout struck objects landing city street. P lead bare wire grounded. Cut off ignition. 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.