Part Number: MC0541153

U-BOLT
Qty

Short delay in shipment:
Stock expected 2021-03-12

U-BOLT

Product Details

Cessna Landing Gear U-Bolt

 

  • Save $$$
  • FAA approved ICA allows 1200 hrs service life instead of 1000 hrs as per SE78-68
  • Vacuum re-melt crankshaft steel alloy for extreme fatigue resistance
  • Rolled "J" threads instead of cut threads for twice the fatigue resistance
  • "J" style nuts and washers included

 

 

U-Bolt History and Maintenance 

By Dave McFarlane

 

U-Bolts take immense vibration and cyclic stress loading from landing and taxiing on imperfect runways. The long Cessna landing gear legs have tremendous twisting leverage on the U-Bolts. Every imperfection you feel while taxiing or operating on the runway is magnified to large stress forces on the U-Bolts that clamp the gear to the outboard fuselage support forgings. The Cessna U-Bolts are made from standard 4130 Steel with inclusions and other imperfections in the metal. The standard sharp threads are cut during Cessna manufacture. The cut threads allow stress concentration of the large stress forces in the sharp “V” of the thread where the U-Bolts are often found broken. When the aircraft is operated with broken U-Bolts, the weight of the airplane and the inboard attachment bolt keeps the landing gear in place, but the twisting gear stress results in hammering vibration on the gear forgings. 

 

If you listen for it, you can hear a broken U-Bolt in the cabin during taxi or you can check for a broken U-Bolt by kicking the tire while holding your finger between the gear leg and the fuselage structure. You will feel movement if the U-Bolt is broken. This hammering will eventually start cracks in the aluminum gear forging and the forging must be replaced - a very expensive repair. It is also recommended to replace the inboard gear support bolt if the aircraft has been operated with a broken U-Bolt. The inboard bolt is a special high strength magnafluxed bolt that is critical to landing gear security. Because of the U-Bolt failure problem, Cessna issued Service Bulletin SE78-68 requiring periodic inspection of the U-Bolts and replacement of the U-Bolts every 1000 hours to prevent failure and to prevent continued operation with failed U-Bolts. Proper torque process and value are also very important to prevent U-Bolt failure.

 

McFarlane U-Bolts are manufactured from higher strength 4340 Crankshaft Steel that has been re-melted under vacuum to remove imperfections in the steel. The threads are roll formed, which strengthens the threads by perfecting the grain structure of the metal that drastically improves fatigue resistance. The “J” style rolled threads are formed with a radius in the bottom of the thread “V” that spreads out the stress loading. McFarlane furnishes new nuts that are designed to work effectively with the “J” thread design. The McFarlane U-Bolts are then carefully heat treated and tempered for perfection in strength and fatigue resistance. Our FAA approved Instructions for Continuous Airworthiness (ICA) conservatively recommend 1200 hours between U-Bolt replacements.

 

 

warningWARNING: Cancer and/or Reproductive Harm - www.P65warnings.ca.gov

Supersedures

OEM Part Number McFarlane Part Number Comment
0541153 MC0541153

Eligible Aircraft

Make Series Model Beginning S/N Ending S/N Quantity Per Aircraft Location Comment Eligibility Chart
Cessna 172 172 28000 46754 2 LANDING GEAR 7435
Cessna 172 172A 46755 47746 2 LANDING GEAR 7435
Cessna 172 172B 17247747 17248734 2 LANDING GEAR 7435
Cessna 172 172C 17248735 17249544 2 LANDING GEAR 7435
Cessna 172 172D 17249545 17250572 2 LANDING GEAR 7435
Cessna 172 172E 17250573 17251822 2 LANDING GEAR 7435
Cessna 172 172F (T-41A) 17251823 17253392 2 LANDING GEAR 7435
Cessna 172 172G 17253393 17254892 2 LANDING GEAR 7435
Cessna 172 172H (T-41A) 17254893 17256512 2 LANDING GEAR 7435
Cessna 172 172I 17256513 17257161 2 LANDING GEAR 7435
Cessna 172 172K 17257162 17259223 2 LANDING GEAR 7435
Cessna 172 F172D F172-0001 F172-0018 2 LANDING GEAR 7435
Cessna 172 F172E F172-0019 F172-0085 2 LANDING GEAR 7435
Cessna 172 F172F F172-0086 F172-0179 2 LANDING GEAR 7435
Cessna 172 F172G F172-0180 F172-0319 2 LANDING GEAR 7435
Cessna 172 F172H F17200655 F17200754 2 LANDING GEAR 7435
Cessna 172 F172H F172-0320 F172-0654 2 LANDING GEAR 7435
Cessna 172 FR172E FR17200001 FR17200060 2 LANDING GEAR 7435
Cessna 172 FR172F FR17200061 FR17200145 2 LANDING GEAR 7435
Cessna 172 FR172G FR17200146 FR17200225 2 LANDING GEAR 7435
Cessna 172 P172D P17257120 P17257188 2 LANDING GEAR 7435
Cessna 172 R172E (T-41B,C,D) R172-0001 R1720335 2 LANDING GEAR 7435
Cessna 172 R172F (T-41D) R172-0336 R172-0409 2 LANDING GEAR 7435
Cessna 172 R172G (T-41C,D) R1720410 R1720444 2 LANDING GEAR 7435
Cessna 172 R172H (T-41D) R1720445 R1720620 2 LANDING GEAR 7435
Cessna 175 175 55001 56238 2 LANDING GEAR 7435
Cessna 175 175A 56239 56777 2 LANDING GEAR 7435
Cessna 175 175B 17556778 17557002 2 LANDING GEAR 7435
Cessna 175 175C 17557003 17557119 2 LANDING GEAR 7435
Cessna 182 182 33000 33842 2 LANDING GEAR 7435
Cessna 182 182A 33843 51556 2 LANDING GEAR 7435
Cessna 182 182B 51557 52358 2 LANDING GEAR 7435
Cessna 182 182C 52359 53007 2 LANDING GEAR 7435
Cessna 182 182D 18253008 18253598 2 LANDING GEAR 7435

Related Documents

Product Catalogs and Price Lists

Current McFarlane Product Catalog

Press Releases

2013-09-24 Can You Stop Nose Gear Shimmy?

PMA Lists

McFarlane Aviation, Inc. PMA Supplement 146

Instructions for Continued Airworthiness

ICA, U-bolt, Cessna

Eligibility Charts

ELIGIBILITY, U-Bolts for Cessna Landing Gear