# Relationship history for MSHA mine 1518837

Current hierarchy: **Leonard  Hendrickson → Hendrickson Equipment, Inc. → A24**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Leonard  Hendrickson → A24; 2000-09-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Hendrickson Drilling LLC → A24; 2004-12-30 to 2011-11-08; source msha-controller-operator-history
- **controller_controls_mine:** Leonard  Hendrickson et al → A24; 2004-12-30 to 2010-04-22; source msha-controller-operator-history
- **controller_controls_operator:** Leonard  Hendrickson et al → Hendrickson Drilling LLC; 2004-12-30 to 2010-04-22; source msha-controller-operator-history
- **controller_controls_operator:** Robert  Hendrickson et al → Hendrickson Drilling LLC; 2004-12-30 to 2010-04-22; source msha-controller-operator-history
- **controller_controls_mine:** Leonard  Hendrickson → A24; 2010-04-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Leonard  Hendrickson → Hendrickson Drilling LLC; 2010-04-23 to 2011-11-08; source msha-controller-operator-history
- **controller_controls_mine:** Ryan  Johns → A24; 2011-08-29 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Rhyno Corp LLC → A24; 2011-11-09 to 2018-10-11; source msha-controller-operator-history
- **controller_controls_operator:** Ryan  Johns → Rhyno Corp LLC; 2011-11-09 to 2018-10-11; source msha-controller-operator-history
- **operator_operates_mine:** Hendrickson Equipment, Inc. → A24; 2018-10-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Leonard  Hendrickson → Hendrickson Equipment, Inc.; 2018-10-12 to current/open; source msha-controller-operator-history