Bell Helicopter 7- A Sbsidiarv of Textron InC EXAMINATION OF A TAILROTOR DRIVESHAFT ASSEMBLY FROM A MODEL 407 OPERATED BY PAPILLON AIRWAYS, INC.

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1 Bell Helicopter 7- A Sbsidiarv of Textron InC - REPORT NO.: DATE:8 May 2000 EXAMINATION OF A TAILROTOR DRIVESHAFT ASSEMBLY FROM A MODEL OPERATED BY PAPILLON AIRWAYS, INC. I

2 ;<.I Bell Helicopter b i 3):C i ENGINEERING DATA MODEL NO. OF PAGES 13 1 REPORTNO. DATE: 8 May 2000 TITLE EXAMINATION OF A TAILROTOR DRIVESHAFT ASSEMBLY FROM A MODEL OPERATED BY PAPILLON AIRWAYS, INC.

3 a Bell Helicopter i 3):C ' 0 TABLE OF CONTENTS Paqe HISTORY AND RELATED DATA INTRODUCTION DISCUSSION CONCLUSION FIGURES 1 View of parts from a tailrotor driveshaft assembly as received by the Field Investigations Laboratory View, forward and aft, of forward hanger with outer ring of hanger bearing still in place View of worn ball path on outer ring of forward hanger bearing View of inner ring of forward hanger bearing View of ball path on the inner ring of the forward hanger bearing. Arrows point to cage material rolled onto the surface of the ring View of grease and pieces of cage and seal membrane from the forward hanger bearing View of cage material and seal membrane from the forward hanger bearing View of pieces of cage seen in Figures 6 and 7 after bearing degreased and cleaned. Damage to fracture surfaces did not allow identification of fracture mode..., View of balls from the forward hanger bearing. Heavy wear and damage was seen on the surface of the balls I

4 Bell Helicopter i 9:C i :a TABLE OF CONTENTS (CONT) 10 View, forward and aft, of the aft hanger bearing. A fair amount of grease was seen outside the bearing Views of aft hanger bearing showing the good condition of the seals View of aft hanger bearing with seal removed showing adequate lubrication inside the bearing View of aft hanger bearing after being degreased and cleaned showing the cage in good condition View of ball path of inner and outer rings from the after hanger bearing View of inner and outer surface of the cage of the aft bearing. Arrows indicate worn areas where the cage rubbed on the inner and outer rings II

5 a ' 0 Bell Helicopter i *:C i A Shsidiary of Textron Inc HISTORY AND RELATED DATA Helicopter Model Registration No. Serial No. Total Time Operation Operator Base of Operations Problem Type of Discovery Date Part(s) Name Part No. Serial No. Total Time CPR No. Name Part No. Serial No. Total Time CPR No. Name Part No. Serial No. Total Time CPR No. Name Part No. Serial No. Total Time Manufactured by CPR No. N 175PA hours Papillon Airways, Inc. Grand Canyon, AZ Accident 16 April 2000 Shaft (fan, tailrotor drive) A-FS 1213 Not Reported Hanger (bearing, aft, fan shaft) A-FS 551 Not Reported Hanger, (bearing, fwd, fan shaft) A-FS 2606 Not Reported Ball bearing (hanger, tailrotor) - 2 each FWd (B ) Aft (B ) hours NHBB Fwd ( ) Aft ( ) 1

6 Bell Helicopter XC i I' INTRO D UCTl ON Parts from a tailrotor driveshaft assembly from a Model operated by Papillon Airways, Inc. were received in the Field Investigations Laboratory for examination. The (S/N ) was involved in an accident on April 16,2000. The operator reported experiencing severe vibration during flight. An autorotation to a clearing was accomplished. During the landing, the tail skid and tail rotor hit the ground. Later inspection of the aircraft revealed the forward hanger bearing from the oil cooler driveshaft had separated. In addition, the gearbox support was reported to have cracked. 2

7 Bell Helicopter CONCLUSION The forward hanger bearing had separated. The cage was in several pieces. A fracture mode could not be identified for the forward hanger bearing cage due to the damage to the fracture surfaces. Damage was seen on both rings from rotation of the inner within the outer after the cage came apart. The aft hanger bearing was in good condition. However, wear marks were observed on the cage where it was making contact with the rings. 3

8 a ' 0 Bell Helicopter ) i XC A Sllbsidiary of Textron Inc DISCUSSION The parts from a Model tailrotor driveshaft shown in Figure 1 as they were received by the Field Investigations Laboratory. The forward hanger bearing (P/N ; S/N ) had disintegrated. Heavily damaged ball paths on the inner and outer rings of the bearing were observed. In addition, cage material was observed rolled onto the surface of the inner ring as shown in Figure 5. The cage from the forward hanger bearing fractured into several pieces. The remnants of the cage are shown in Figure 8. Due to the extent of damage undergone by the cage, a fracture mode could not be established. In addition, balls from the hanger bearing showed heavy wear and damage on the surface as seen in Figure 9. Only 11 balls out of 13 were received. The aft hanger bearing was received still installed on the shaft and in the hanger. Inspection of the bearing revealed it to be in good condition, with the seals properly installed. Removal of the seals showed the bearing had an adequate amount of grease (Figures 10-12). The ball paths of the inner and outer rings were smooth and had uniform wear patterns. The cage was in good condition. All the cage welds were intact. Wear was observed on the inner and outer diameters of the cage (see Figure 15). This wear was from the cage rubbing on the inner and outer rings of the aft hanger bearing. A small wear band was seen on the rings from the cage making contact (Figure 14). Grease from the forward and aft hanger bearings was analyzed and it conformed to & the required grease specification of Royco 13 (MIL-G-25013) A minimum hardness of 58 HRC was required for the rings and the balls of the hanger bearings. The inner and outer rings on the forward hanger bearing had hardnesses of 59 and 58 HRC, respectively. A ball had a hardness of 62. Likewise the aft hanger bearing also conformed to the hardness requirements. The inner and outer rings had hardnesses of 61 and 59 HRC, respectively while a ball had a hardness of 62 HRC. 4

9 Bell Helicopter LiW :e Aft Fwd I Figure 1 View of parts from a Model tailrotor driveshaft as received by the Field Investigations Laboratory Forward side Aft side Figure 2 View, forward and aft, of forward hanger with outer ring of hanger bearing still in place. 5

10 vw Bell Helicopter ' e ' Worn ball path Damaged seal Figure 3 View of worn ball path on outer ring of forward hanger bearing. Figure 4 View of inner ring of forward hanger bearing. 6

11 Bell Helicopter i *:C i :. A Shsidiary of Textron Inc.. Figure 5 View of ball path on the inner ring of the forward hanger bearing. Arrows point to cage material rolled onto the surface of the ring. Figure 6 View of grease and pieces of cage and seal membrane from the forward hanger bearing. 7

12 Bell Helicopter 1 i $14 ' 0 Figure 7 View of cage material and seal membrane from the forward hanger bearing. Figure 8 View of pieces of cage seen in Figure 6 and 7 after bearing degreased and cleaned. Damage to fracture surfaces did not allow identification of fracture mode. 8

13 Bell Helicopter i * : 4' 0 u A Slrbsidiary of Textran Inc 7- Mechanical damage Figure 9 View of balls from the forward hanger bearing. Heavy wear and damage was seen on the surface of the balls. 9

14 Bell Helicopter b m f l Forward side Aft side Figure 10 View, forward and aft, of the aft hanger bearing. A fair amount of grease was seen outside the bearing. 10

15 Bell Helicopter ) i X C i A Slibsidiary of Textron Inc Figure 11 Views of aft hanger bearing showing good condition of the seals. Figure 12 View of aft hanger bearing with seal removed showing adequate lubrication inside the bearing. 11

16 Bell Helicopter XC i ' 0 Figure 13 View of aft hanger bearing after being degreased and cleaned showing the cage in good condition. Smooth and uniform wear pattern of ball path \ band contact ;age Figure 14 View of ball path of inner and outer rings from the aft hanger bearing. 12

17 Bell Helicopter i *:C i A Slibsidiary of Tex tron Inc Wear from contact with inner ring Wear from contact with outer ring I Figure 15 View of inner and outer surface of the cage of the aft bearing. Arrows indicate worn areas where the cage rubbed on the inner and outer rings. 13

MAIN ROTOR BLADE EXPANDABLE BOLT P/N

ALERT SERVICE BULLETIN 412-09-137 23 November 2009 Revision A, 16 July 2018 MODEL AFFECTED: SUBJECT: 412/412EP MAIN ROTOR BLADE EXPANDABLE BOLT P/N 412-010-137-103 HELICOPTERS AFFECTED: Serial numbers