REPORT NO.: 407 DATE:8 May 2000 - EXAMINATION OF A TAILROTOR

OPERATED BY PAPILLON AIRWAYS, INC. DRIVESHAFT ASSEMBLY FROM A MODEL 407

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Bell Helicopter 7- A Sbsidiarv of Textron InC

;<.I Bell Helicopter b i 3):C i A Subsidiary of Textron Inc

ENGINEERING DATA

MODEL 407 NO . OF PAGES 13

1 REPORTNO. 407 DATE: 8 May 2000

TITLE EXAMINATION OF A TAILROTOR

DRIVESHAFT ASSEMBLY FROM A MODEL 407 OPERATED BY PAPILLON AIRWAYS, INC.

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A Subsidiary of Textron Inc Bell Helicopter i 3):C a

407

TABLE OF CONTENTS Paqe

HISTORY AND RELATED DATA . . . . . . . . . . . . . . . . . . . . . . . . 1

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

DISCUSSION.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

CONCLUSION.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

FIGURES

1 View of parts from a 407 tailrotor driveshaft assembly as received by the Field Investigations Laboratory . . . . . . . . . . . . . . . . . 5

2 View, forward and aft, of forward hanger with outer ring of hanger bearing still in place. . . . . . . . . . . . . . . . . . . . . . 5

3 View of worn ball path on outer ring of forward hanger bearing . . . . . 6

4 View of inner ring of forward hanger bearing . . . . . . . . . . . . . . 6

5 View of ball path on the inner ring of the forward hanger bearing. Arrows point t o cage material rolled onto the surface of the ring . . . . . 7

6 View of grease and pieces of cage and seal membrane from the forward hanger bearing . . . . . . . . . . . . . . . . . . . . . . . . 7

7. View of cage material and seal membrane from the forward hanger bearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

8 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 . . . , . . . . . . . . . . . . . . . . . . . . . . . . 8

9 View of balls f rom the forward hanger bearing. Heavy wear and damage was seen on the surface of the balls . . . . . . . . . . . . . 9

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: a Bell Helicopter i 9:C i A Subsidiary of Textron Inc

407

TABLE OF CONTENTS (CONT)

10 View, forward and aft, of the aft hanger bearing. A fair amount of grease was seen outside the bearing . . . . . . . . . . . . . . . . 10

11 Views of aft hanger bearing showing the good condition of the seals. . . 11

12 View of aft hanger bearing with seal removed showing adequate lubrication inside the bearing . . . . . . . . . . . . . . . . . . . . . 11

13 View of aft hanger bearing after being degreased and cleaned showing the cage in good condition . . . . . . . . . . . . . . . . . . 12

14 View of ball path of inner and outer rings from the after hanger bearing . 12

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

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A Shsidiary of Textron Inc Bell Helicopter i *:C i a

407

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.

HISTORY AND RELATED DATA

407 N 175PA 53154 1847.8 hours

Papillon Airways, Inc. Grand Canyon, AZ

Accident 16 April 2000

Shaft (fan, tailrotor drive) 406-040-320-1 0 1 A-FS 1213 Not Reported 202621 00

Hanger (bearing, aft, fan shaft) 406-040-31 7-1 01 A-FS 551 Not Reported 20262200

Hanger, (bearing , fwd, fan shaft) 406-040-322-1 01 A-FS 2606 Not Reported 20262300

Ball bearing (hanger, tailrotor) - 2 each 407-340-339-1 03 FWd (B-99-0536) Aft (B-99-0683) 517.7 hours NHBB Fwd (20262400) Aft (20262500)

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Bell Helicopter X C i I' A Subsidiary of Textron Inc

407

INTRO D UCTl ON

Parts from a tailrotor driveshaft assembly from a Model 407 operated by Papillon Airways, Inc. were received in the Field Investigations Laboratory for examination. The 407 (S/N 531 54) 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.

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Bell Helicopter 407

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 af t hanger bearing was in good condition. However, wear marks were observed on the cage where it was making contact with the rings.

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A Sllbsidiary of Textron Inc Bell Helicopter ) i X C a

407

DISCUSSION

The parts from a Model 407 tailrotor driveshaft shown in Figure 1 as they were received by the Field Investigations Laboratory. The forward hanger bearing (P/N 407- 340-339-1 03; S/N 6-99-0536) 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 1 0 - 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 t o & 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 5 9 and 5 8 HRC, respectively. A ball had a hardness of 62. Likewise the aft hanger bearing also conformed t o the hardness requirements. The inner and outer rings had hardnesses of 61 and 5 9 HRC, respectively while a ball had a hardness of 62 HRC.

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Bell Helicopter LiW : e A Subsidiary of Textron Inc

407

Aft

Forward side

Fwd

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Figure 1 View of parts from a Model 407 tailrotor driveshaft

as received by the Field Investigations Laboratory

Aft side

Figure 2 View, forward and aft, of forward hanger

with outer ring of hanger bearing still in place.

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Bell Helicopter vw ' e A Subsidiary of Textron Inc

407'

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.

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Bell Helicopter i *:C i :. A Shsidiary of Textron Inc

407

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Figure 5 View of ball path on the inner ring of the forward hanger bearing. Arrows point t o 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.

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Bell Helicopter 1 i $14 ' 0

A Subsidiary of Textron Inc

407

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.

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Bell Helicopter i * : 4 u ' 0

A Slrbsidiary of Textran Inc 407

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Figure 9 View of balls from the forward hanger bearing.

Heavy wear and damage was seen on the surface of the balls.

Mechanical damage

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Bell Helicopter b m f l A Subsidiary of Textron Inc

407

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.

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Bell Helicopter ) i X C i A Slibsidiary of Textron Inc

407

Figure 1 1 Views of af t hanger bearing showing good condition of the seals.

Figure 12 View of aft hanger bearing with seal removed

showing adequate lubrication inside the bearing.

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Bell Helicopter X C i ' 0

Smooth and uniform wear pattern of ball path

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A Subsidiary of Textron Inc 407

Figure 13 View of aft hanger bearing after being degreased and cleaned showing the cage in good condition.

band contact

;age

Figure 14 View of ball path of inner and outer rings from the aft hanger bearing.

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Bell Helicopter i *:C i A Slibsidiary of Tex tron Inc

407

Wear from contact with inner ring

Wear from contact with outer ring

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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.

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