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How engine is mounted in wing is restricting motion in any direction but is it still resistant to shock loads, or is there any mechanism inside engine associated to bearings that will absorb shock loads that occur in spools?

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    $\begingroup$ Related Thrust bearing. Engine spools already experiment axial loads in flight, due to the unbalance of forwards and rearwards thrusts inside the engine. Thrust bearings are used to resist this unbalance and maintain the spools in place. $\endgroup$ – mins Jan 25 '17 at 6:27
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    $\begingroup$ The wing joint also absorbs a lot of the landing impact as the wings flex down, either at the wing joint itself or if the gear are mounted in the wings there. It may help to understand that the wing is not a rigid system, so I wouldn't really qualify it as a "shock load". Aside from that the gear damping mechanism takes a lot of the "shock" from landing as well, so not a lot is transferred to the engine. This may be more of an issue for turbofans that have gear mounted in the nacelles. $\endgroup$ – Ron Beyer Jan 25 '17 at 6:33
  • $\begingroup$ @ron beyer, there are cases which we find bearing ball indentation in bearing races, especially on outer race roller path. btw it is a low bypass turbofan so shock is comparitively more while landing. how about commercial aircrafts? is this the same case on high bypass too? $\endgroup$ – Anso Mamachan Jan 25 '17 at 6:39
  • $\begingroup$ This may be interesting to know if aircraft landing with arresting systems are specifically hardened. $\endgroup$ – mins Jan 25 '17 at 7:35
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    $\begingroup$ @Ron Beyer your comment is an excellent answer. Shock absorption (stretching load force over greater time) can be accomplished from the wheels on up to wing flex. The entire engine would experience landing "shock" (as would passengers) as long as there is not any gap in the bearing. (It would be designed to handle the same G loads as the rest of the plane (with adequate safety margin)). $\endgroup$ – Robert DiGiovanni Aug 26 '19 at 18:25
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"Shock" loads on landing can be transmitted to engine components. The original poster appears to be asking about turbine engines specifically. The significance of a hard landing on the engine spools themselves will be shaft flex and case flex, and the possibility of blade rubbing (and erosion). This is a concern with a hard landing, and something that must be considered. There are not "shock absorbing" features or capabilities built into bearings in engine spools; these are intended to have minimal friction in rotation, but no concentric movement about their axis. It is possible in severe turbulence, and in a hard landing, to experience case or blade damage or wear, and there are inspections prescribed for certain components in certain engines to address this.

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Back in the early days of the deployment of the C-5 cargo plane, overflexure of the wing-to-fuselage attachment during landings was identified as one reason for the serious cracking in that area which the first revision of the C-5 was susceptible to.

One cause of the overflexure was that during a hard landing, at the moment of touchdown the mass of the engines and the wing itself would sag the wingtips downward as the landing gear was absorbing the shock loads.

One of my engineering professors was involved in a design exercise to study the feasibility of a thrust-vectoring system which, upon touchdown, would briefly deflect the engine exhaust downwards to lift the engines and wing upward and limit the downsag, and thereby extend the fatigue lifetime of the wing-to-fuselage attachment.

To my knowledge, nothing ever came of this proposal- but it represented a case where shock loads on the fuselage caused by the inertia of the engines needed to be managed.

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There are no mechanically significant shock loads on an airplane engine in normal operation.

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    $\begingroup$ adding some detail and references to your answer will keep the predators away. Your answer is generally correct. $\endgroup$ – Robert DiGiovanni Aug 26 '19 at 18:27

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