BALTIMORE, MD, USA
N2100B
Schweizer 269C
The police helicopter was performing a police mission less than 500 above ground level when the engine lost power. The pilot was unable to reach a suitable landing area and maintain rotor rpm. The helicopter struck trees and a light pole, landed hard on a road, and slid into a fence. Examination revealed the #2 connecting rod had separated from the crankshaft. A torque check on the remaining connecting rod bolts found all below the minimum specified. A work action (strike) had been in effect at the engine manufacturer at the time of engine assembly, and production continued with management and replacement workers. During assembly the crankshaft had been replaced for an unknown reason. After the crankshaft was replaced, new connecting rods were attached, but not properly tightened. Replacement workers manned the two assembly stations identified as most probable for replacement of the crankshaft and failure to tighten the connecting rod bolts. Although long time employees knew the correct procedures for documentation of a replaced crankshaft, no specific written instructions were available for the replacement employees. The engine failed at 45.7 hours total time.
HISTORY OF FLIGHT On November 4, 1998, at 1428 Eastern Standard Time, a Schweizer 269C, N2100B, was destroyed when it impacted terrain during a forced landing in Baltimore, Maryland. The certificated commercial pilot/police officer was fatally injured and the aerial observer received serious injuries. The helicopter, owned by U.S. Leaseco Inc., maintained by Helicopter Transport Services, Inc., and operated by the Baltimore Police Department Helicopter Unit, was on an aerial observation flight at the time of the accident. Visual meteorological conditions prevailed, and no flight plan was filed for the public use flight conducted under 14 CFR Part 91. According to records, the helicopter was flown that morning for 2 1/2 hours. No discrepancies were recorded for that flight. The observer reported the flight departed Martin State Airport about 1310. About 1420, a police ground unit requested assistance from the helicopter flight crew. According to the aerial observer, the assist consisted of not flying below 500 feet mean sea level, and maintaining an airspeed of about 30 to 40 mph, while watching a vehicle. When released from their assignment, the pilot added power, climbed and turned left. At the same time the helicopter started shaking left and right very hard, and the aerial observer reported that he observed smoke in front of the helicopter. The pilot did not say anything. The helicopter was directly over an alley or small street. The pilot initiated an autorotation. The helicopter continued to turn to the south, toward a row of houses. The pilot turned right to clear the houses and then back toward the south. The skids struck the tops of trees, and then a light pole, which folded up. The helicopter was coming down fast, which was not normal. The helicopter struck the middle of an east/west street traveling south. It momentarily became airborne as they bounced in front of a moving police car, and continued across the street, accompanied by a massive banging noise. The helicopter slid through a fence and came to rest on its left side. The aerial observer reported that he was still conscious. Another police officer was at the site within seconds, and called to the pilot who was unconscious. The police officer then tried to remove their seat belts, but could not release them and cut them instead. They were subsequently pulled out of the helicopter. The aerial observer further added, "When the engine failure occurred, there was no place to go." A police officer, located about two city blocks west of the suspect vehicle, stated: "...(I heard) something on the radio. I am not sure if it was a ground unit or Fox (the helicopter). Out of the corner of my eye I observed something, I glanced up and saw (the helicopter) coming down. It appeared that the rotor blade...wasn't spinning normally. It appeared to be slow." Other witnesses reported hearing a loud pop and saw smoke trailing from the helicopter. A police officer reported that "the helicopter made a sharp hook through two buildings and hit the street approximately 5 feet in front of my car." A small post crash fire developed behind the occupants, which was extinguished by police officers prior to the arrival of fire trucks. The accident occurred during the hours of daylight at 39 degrees, 17.14 minutes north latitude, and 76 degrees, 37.87 minutes west longitude. PERSONNEL INFORMATION PILOT The pilot held a commercial pilot certificate with ratings for airplane single and multi-engine land, rotorcraft-helicopter, and instrument helicopter. He was last issued a second class Federal Aviation Administration (FAA) airman medical certificate on September 29, 1998. According to the NTSB Pilot/Operator Aircraft Accident Report form, filled out by the Baltimore Police Department, the pilot's total flight experience was 16,000 hours, with 14,000 in make and model. In the preceding 90 days and 30 days, he had flown 200 hours and 70 hours respectively. According to the pilot's training file, he last received a flight check on March 27, 1998. The checkride included autorotations that were straight in, with turns, from a hover, and with a power recovery. The comment from the check airman was "Good Ride." AIRCRAFT INFORMATION The helicopter was a Schweizer 269C that had been modified with the installation of police radios and an external searchlight. No navigation radios were installed. The maximum certificated gross weight of the helicopter was 2,050 pounds. A weight and balance for the accident flight was computed by Schweizer Aircraft Company at 1,954 pounds, and the weight at the time of the accident as 1,860 pounds. WRECKAGE AND IMPACT INFORMATION Examination at the accident site revealed ground scarring and debris scattered in a southerly direction for 89 feet. The first contact with a ground object was at the top of a tree estimated to be 40 to 45 feet tall, and located 20 feet south of a dwelling. Thirty feet further along, a 20-foot-tall light pole was laying on the ground. Blue paint-transfer marks, similar in color to the helicopter, were found on the pole. About 17 feet beyond the pole, was a 3-foot-long scrape in the asphalt. Twelve feet beyond the scrape, there were two additional, parallel scrapes, 9 feet long, and 9 feet apart. The helicopter came to rest 21 feet beyond the parallel scrapes, lying on its left side. The landing skids were fragmented, and the tail boom was separated from the structure. No evidence of a mechanical malfunction was found with the main rotor, tail rotor, drive system, or flight controls. According to a report from Schweizer aircraft: "...There was minimum chordwise compression of the main rotor blade airfoils...There was flapwise bending of the blue and yellow blades...There was minor impact damage to the tips of the red and blue blades. The red blade had a down bend about mid span and tip impact deformation...Tail rotor drive continuity was established...The tail rotor blades exhibited side impact signatures with damage to the airfoil fiberglass...The tip caps were cracked and separated...All flight controls were verified to have been intact and functional prior to impact...All blades on the [engine] impeller were intact...." Holes which measured 4 inches on the top, and 2 inches on the bottom, were found on the engine case near the number 2 cylinder. A visual examination through the holes revealed the number 2 connecting rod was not attached to the crankshaft. The engine was taken to Textron Lycoming for disassembly. After the crankcase was split, the crankshaft was removed with the number 1, 3 and 4 connecting rods attached. Measurements were made of the stretch on the connecting rod bolts, and of the torque needed to tighten the bolts. All measurements taken were less than Textron Lycoming specified in their production documents. MEDICAL AND PATHOLOGICAL INFORMATION The pilot's toxicological testing report from the FAA Toxicology Accident Research Laboratory, Oklahoma City, Oklahoma was negative for drugs and alcohol. The pilot's autopsy was conducted by the Medical Examiner's Office, City of Baltimore, Maryland. TESTS AND RESEARCH The fractured connecting rod bolts from the number 2 connecting rod were examined at the Safety Board Materials Laboratory in Washington, DC. According to their factual report: "...The fracture face on the [number 2 connecting rod] bolt piece...was typical of a tensile separation with a degree of bending evolved...[On the other bolt] Examination of the fracture face revealed a flat surface with an arced periphery, that was perpendicular to the bolt axis and a final separation lip at 45 degrees. Further examination in a scanning electron microscope (SEM)...revealed the banding confirming a fatigue separation. The fatigue initiation location was within the damaged area... ADDITIONAL INFORMATION ENGINE HISTORY The engine, an HIO-360-D1A, S/N L-27694-51A was manufactured at the Textron Lycoming factory in Williamsport, Pennsylvania. According to company production records, assembly began on January 29, 1998. As the engine progressed though the various assembly steps, they were signed off. After assembly, the engine was placed in a test cell and run. No problems were noted, and the engine was prepared for shipment. On February 17, 1998, the engine was picked up by Helicopter Transport Services Inc., and trucked to Baltimore Maryland. According to the engine disassembly report from Textron Lycoming, and witnessed by FAA and Safety Board investigators: "...According to maintenance personnel at Helicopter Transport Services, Baltimore, MD, prior to installing the engine in N2100B, the # 1 cylinder was removed and utilized as a borrowed part [cannibalized]. A replacement cylinder was later reinstalled on the subject engine...." Examination of records from Helicopter Transport Services, Inc, revealed that a spare cylinder was listed in the parts allocated to the engine being built-up. The reason for the spare cylinder was not recorded, and there was no record of a cylinder change in the permanent engine record in accordance with FAR 43. On October 22, 1998, HIO-360-D1A, serial number L-27694-51A was installed at airframe time 680.8 hours. On October 23, 1998 a 100-hour inspection was conducted on N2100B. According to daily flight sheets, the following discrepancy was found for October 28, 1998, 16.9 hours after the engine change: "A/C has mid freq vibs at all power settings, increases as additional power is applied. Vibs felt in controls and seat. Mags OK. Uses 13 Gal Per Hr when flown predominately at econo cruise settings." The corrective action for the discrepancy was to change the fuel servo. This discrepancy was not recorded again. The helicopter continued to be used in police service until the time of the accident, at which point the engine had accumulated 45.7 hours of operation, and the airframe had accumulated 726.5 hours. TEXTRON LYCOMING - Work Action A work action (strike) was in place at Textron Lycoming from August 4, 1997, to March 1, 1998, during which time, the FAA increased surveillance. According to a FAA inspector who participated in the increased surveillance, replacement workers were hired and trained to perform various assembly operations. Textron Lycoming used a recruitment company, and in the beginning specified that all replacement workers have mechanics certificates. As the strike continued, and the available pool of applicants decreased, the requirement for a mechanic's certificate was dropped. Experienced Textron Lycoming employees were strategically placed in assembly areas to provide supervision and an experience base. TEXTRON LYCOMING - Engine Assembly Paperwork During engine production, various items were recorded and retained as part of the permanent engine assembly record. Included in these were the shop floor control record and Form ET-003. Examination of the shop floor control record for the engine revealed that the original crank shaft serial number had a single line drawn through it, and a second number entered above. The second serial number matched the serial number found on the crank shaft during engine disassembly. In addition, the crankshaft end clearance was recorded as 0.009 inches. According to page 10 of 16, for step 130, the acceptable crankshaft end clearance was 0.009 to 0.016 inches. According to Quality Control Order 201 dated September 15, 1995, Form ET-003 was listed as a document that was retained by the Quality Assurance Department as part of the engine records. The form was revised on July 25,1997, and the reference to Form ET-003 was dropped. This was the current form at the time of assembly of the accident engine. In a letter, the Director, Quality Assurance reported that Form ET-003 had been in continuous use for many years. In a follow-up telephone interview, the Director, Quality Assurance reported that the absence of Form ET-003 from the July 25, 1997, revision was an oversight, and not an intentional deletion. According to the senior accident investigator for Textron Lycoming, who had previous experience in engine production both as an assembler and an inspector, Form ET-003 was used to record all anomalies encountered during production. Prior to the engine leaving the plant, these discrepancies would be reviewed by an inspector and cleared, or the engine returned to an earlier phase of production for further examination and correction. He further stated that it was the responsibility of the person who rejected a part or noted that it failed an inspection to record that data on form ET-003. Examination of Textron Lycoming Form ET-003 revealed no entered information about a failed inspection or rejected part. Textron Lycoming was unable to supply specific written instructions for the use of Form ET-003, as reported by their senior accident investigator. According to a letter from the Director, Quality Assurance at Textron Lycoming, and addressed to the FAA Manufacturing Inspection District Office that had oversight authority over the company, the most probable scenario for improper engine assembly was: "...The assembly of S/N L-27694-51A was initiated on Friday January 30, 1998, and the crankshaft (SN I 32876) Assembly Operation # 110 and # 120 were accomplished the same day. Operation # 110 assembles the rods to the shaft with proper torque/stretch and Operation # 120 inspects the assembly." "At this point the assembled crankshaft is mated to the crankcase. This operation # 130 included an end clearance check between the crankshaft and crankcase. Crankshaft assembly I 32876 did not meet this requirement and was replaced with assembly I 32870. Our belief is that this crankshaft (I 32870) was reassembled with the connecting rods, was torqued to approximately 20ft lbs. using an air-powered wrench (normal procedure). Everything up to this point was done on the 30th. Normal procedures would then be to stretch the bolts to the final stretch length (2.255"-2.256") using an appropriate torque wrench and measuring bolt stretch. We believe that this operation was missed on Monday February 1, 1998 due to the fact that when the crankshaft was replaced, the routing paperwork [ET-003] was not noted to indicate that operation # 110 was not completed and operation # 120 was not accomplished." Although the scenario submitted by Textron-Lycoming matched the occurrence based upon available evidence, the actual reason for the replacement of the crankshaft was not able to be determined due to lack of available documentation. ENGINE ASSEMBLERS The assembler at station 110 applied for work on November 18, 1997. According to company training records, he was trained from November 18, 1997, to November 23, 1997, on assembly operation 110, the mating of the connecting rods to the crankshaft and torquing the bolts. The person who trained the engine assembler had himself been trained on engine assembly step 110 during the week of October 27, 1997. The assembler at station 130 applied for work on October 7, 1997. No training records were documented when he was trained to conduct assembly at station 130. According to a memo dated May 23, 2000, "...I trained...on operation 130, power section assembly and worked with him for several weeks. It is my opinion that he was proficient in all aspects of operation 130...." The person who conducted the training reported that he was an employee of Textron Lycoming, Engineering Department since 1977, and had responsibility for engine assembly processes and routing. Neither assembler held a mechanics certificate, nor were they required to. Neither person had any previous experience in the assembly of aircraft engines. BALTIMORE POLICE DEPARTMENT According to Baltimore Police Department Tactical Division Directive 2-97, dated July 25, 1997, and signed by the pilot: "...3. Unless air traffic control requirements dictate otherwise, aircraft shall not descend below 500' AGL during routine patrol flights. This applies whether operating day or night...." According to the BWI [Baltimore-Washington Int
inadequate assembly instructions from the engine manufacturer which resulted in improper engine assembly, and subsequent power loss over unsuitable terrain, with insufficient altitude for a successful autorotation.
Source: NTSB Aviation Accident Database
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