NTSB Factual Report

On May 23, 2007, at 1540 central daylight time, a Cessna 421, N4082L, collided with the terrain following a loss of engine power shortly after takeoff from the Spirit of St. Louis Airport (SUS), Chesterfield, Missouri. The pilot received serious injuries. The airplane sustained substantial damage. The 14 Code of Federal Regulations Part 91 flight was operating in visual meteorological conditions and a visual flight rules flight plan was filed. The intended destination was the St. Louis Downtown Airport (CPS), Cahokia, Illinois.

The pilot reported that the right engine suddenly lost power shortly after takeoff at an altitude of about 800 feet above mean sea level (msl) when he was at an indicated airspeed of 135 miles per hour. He stated the needle on the tachometer went to zero. The airplane turned 30 to 40 degrees to the right and banked 50 degrees to the right. He stated he leveled the airplane and added power at which time the airplane again banked to the right.

The pilot stated he informed the air traffic control tower of the problem and he was cleared to land on any runway. He stated he verified that the fuel pumps were on high and he pulled the right engine propeller control back to the stop. He stated that one or both engines then surged so he pushed the propeller control full forward thinking he may be able to regain power, which did not happen.

The pilot reported that runway 8L was in front of him so he concentrated on landing. He determined that he was not going to reach the runway so he elected to land in a dirt field. He stated he lowered the landing gear and aimed to land under power lines that were in his flight path. He stated he attempted to flare the airplane and it impacted the terrain. The left wing tip tank and all three landing gear separated from the airplane during the impact sequence. The pilot stated he turned off the fuel pumps and the battery prior to exiting the airplane.

The airplane was equipped with Teledyne Continental GTSIO-520 engines. Following the accident, the left engine, serial number 219314, was examined and placed on a test bench where it was operated to full power without any deficiencies noted.

Examination of the right engine, serial number, 219318, revealed that all of the teeth on the starter adapter gear and several of the teeth on the crankshaft gear were missing. Several gear teeth and metal filings were located in the oil sump. The torsional damper to shaft gear woodruff key was sheared. The torsional damper was placed on a test bench to determine the damping time. The consecutive tests averaged a damping time of 6.9 seconds. The damping time of a new damper is min/max 1.5 to 3.125 seconds.

The starter gear, crankshaft gear, and separated gear teeth were examined at the Safety Board's Material Laboratory. This examination revealed 15 starter gear teeth and 11 crankshaft gear teeth were fractured near their root. No indications of preexisting cracking were noted. At least two of the starter gear teeth and several of the crankshaft gear teeth displayed spalling and wear at the pitch line of the teeth.

On June 13, 1994, Teledyne Continental issued a Mandatory Service Bulletin, MSB94-4, addressing the possible failure of the starter adapter gear and/or crankshaft gear on GTSIO-520 and GIO-550 engines. On October 31, 2005, Teledyne Continental issued revision, MSB94-4G. The service bulletin called for an inspection of the starter adapter viscous damper and shaft gear backlash every 100 hours of engine operation, and a visual inspection of the starter adapter shaft and crankshaft gear teeth for spalling, pitting, and wear, every 400 hours of engine operation.

The Federal Aviation Administration (FAA) issued Airworthiness Directive (AD) 2005-20-04, effective November 1, 2005, requiring compliance with the Teledyne Continental Mandatory Service Bulletin. The FAA then issued AD 2007-05-15, effective April 16, 2007, which corrected an error in AD 2005-20-04.

The overhauled right engine was installed on the airplane on March 20, 2001. Maintenance records showed the mandatory service bulletin had been complied with when the engine was installed. There was no indication in the maintenance records that either the mandatory service bulletin or the AD had been complied with since the engine was installed. The engine had a total time of 541.9 hours at the time of the accident.

The Cessna 421 Owner's Manual states the following procedures for an engine failure after takeoff at an aispeed above 120 miles per hour:

(1) Mixtures - FULL RICH

(2) Propellers - FULL FORWARD

(3) Throttles - FULL FORWARD (39.5 in. Hg)

(4) Landing Gear - UP

(5) Inoperative Engine - DETERMINE (idle engine same side as idle foot.)

(6) Inoperative Propeller - FEATHER

(7) Establish Bank - 5 degrees Toward good engine.

(8) Climb to Clear Obstacle - 120 MPH IAS

(9) Climb at Best Single-Engine Climb Speed - 120 MPH IAS

(10) Trim Tabs - ADJUST (5 degree bank toward good engine).

(11) Inoperative Engine - SECURE as follows:

(a) Mixture - IDLE CUT-OFF

(b) Fuel Selector - OFF.

(c) Auxiliary Fule Pump - OFF

(d) Magneto Switches - OFF

(e) Alternator Switch - OFF

(f) Cowl Flap - CLOSED

(12) As Soon as Practical - LAND

NTSB Probable Cause

Maintenance personnel failed to comply with an Airworthiness Directive which resulted in the total failure of the starter adapter gear teeth and the crankshaft gear teeth and the pilot failed to follow the published emergency procedures. Contributing to the accident were the low altitude at which the loss of power occurred, the power lines, and the unsuitable terrain which prevented the pilot from adequately flaring the airplane and resulted in the subsequent hard landing.